Phytoremediation Efficiency Research Articles

Influence of Planting Density on the Phytoremediation Efficiency of Festuca arundinacea in cd-Polluted Soil.

Planting density can influence the biomass generation and element uptake capacity of various plants, which are two critical factors that determine the phytoremediation efficiency of plants. A series of 70 d experiments was performed to evaluate the influence of the planting density (10, 15, 20, 25, and 30g seeds·m- 2, namely D10, D15, D20, D25, and D30, respectively) of Festuca arundinacea on the decontamination of Cd-polluted soils. The variations in the biomass yield, falling tissue (senescent and dead leaf tissues) proportion, and Cd extraction capacity of the species under different cultivation strategies were determined. The results showed that the biomass generation of the species per square meter increased as the planting density increased, reached a peak at D20, and then decreased significantly. In addition, planting density can change the proportions of different leaf types, and the highest amount of senescent and dead leaves which accumulated significantly more Cd compared with the emerging and mature leaf tissues was observed at D20. A suitable planting density can also drive the species to secrete more dissolved organic matter (DOM), especially hydrophilic fractionations in to the soil, activating more Cd. Therefore, the phytoremediation efficiency of the species was determined by the dry weight of the falling tissues, which contained more than 75% of the leaf Cd. A suitable planting density can enhance the Cd decontamination capacity of F. arundinacea, and the adjustment of the planting density is a practicable and economical method that can be performed in real fields.

Comparative study on different organic acids for promoting Solanum nigrum L. hyperaccumulation of Cd and Pb from the contaminated soil

Organic acids-assisted phytoremediation is a promising strategy to remove metal pollutants from the soil. However, few reports have focused on the mechanisms of organic acids promoting the uptake of heavy metals by hyperaccumulators. In this study, 5 types of organic acids, namely polybasic carboxylic acids, acidic amino acids, acidic plant growth regulators, phosphoric and gluconic acids, were comprehensively investigated the effects on the solubility of Cd and Pb in the soil along with their uptake by Cd hyperaccumulator Solanum nigrum L. The results indicated that the addition of Hydroxyethylidene-1,1-diphosphonic acid (HEDP) and d-Gluconic acid (D-GA) effectively extracted the most of acid-extractable and some of reducible and oxidizable fractions of Cd and Pb in the soil, with the extraction rates of 64.8% and 34.4% for total Cd and 53.6% and 30.0% for total Pb, respectively. HEDP and D-GA significantly increased the accumulations of Cd (57.1% and 35.0%) and Pb (43.4% and 31.9%) by S. nigrum without the inhibition of its biomass, making the great removal efficiencies of Cd (1.35% and 1.16%) and Pb (0.039% and 0.036%) from the soil. The enhanced phytoremediation efficiency of S. nigrum was due to the increase of the extractable Cd and Pb in the rhizosphere but little changes of soil pH and enzyme activities (catalase and urease). Among all of organic acids, HEDP may be an alternative to EDTA because of its characteristics of environmental friendliness and high efficiency.

Effects of decapitation and root cutting on phytoremediation efficiency of Celosia argentea

Decapitation and root cutting can influence plant physiological features, such as height, dry weight, and transpiration rate, which partly determine the success of phytoremediation. In this study, the effects of three root cutting intensities (10%, 25%, and 33%), decapitation, and their combination on the phytoremediation efficiency of Celosia argentea were evaluated. Decapitation increased the biomass yield of C. argentea roots and leaves and significantly improved the species’ Cd decontamination ability. Root cutting, especially 33% cutting treatment, decreased the root dry weight. The 10% and 25% root cutting treatments increased the leaf biomass yield by 58.6% and 41.4%, respectively, compared with the untreated control, even compensating for the loss of roots, but 33% root cutting decreased the leaf dry weight. Low and moderate root cutting intensity (10% and 25%) increased the leaf Cd content by 33.4% and 24.9%, respectively, and was associated with improved transpiration rate. The highest root and leaf dry weights were observed for the combination of decapitation and 10% root cutting, which increased the biomass yield of underground and aerial parts by 109.9% and 286.2%, respectively. In addition, decapitation offset the negative effects of 33% root cutting on plant growth, indicated by the higher dry weight relative to the control. Decapitated C. argentea accumulated 11.0, 7.5, and 0.7 times more Cd with the 10%, 25%, and 33% root cutting treatments, respectively, compared with the control. The combination of root cutting and decapitation was a practicable and economical method of enhancing the Cd decontamination capacity of C. argentea.

Optimization of integrated phytoremediation system (IPS) for enhanced lead removal and restoration of soil microbial activities

Improving phytoremediation efficiency in lead (Pb) contaminated soil through either bacterial or fungal inoculants have extensively been studied with different successes and limitations. In this study, co-application of bacteria and fungi have been investigated for development of an integrated phytoremediation system (IPS) for efficient Pb removal and restoration of soil microbial and enzymatic activities in degraded soil. For this purpose, Pb tolerant bacterial and fungal strains were firstly analyzed for antifungal and antibacterial activities through disc diffusion method. Afterwards, the co-inoculation studies were performed to investigate the effects on phytoavailability and uptake of Pb by Pelargonium hortorum through soil incubation and pot culture experiments, respectively. Results indicated significant (p < 0.05) antibacterial activity of Mucor spp. against bacterial species (Klebsiella variicola and K. quasipneumoniae). The highest significant increase in extractable Pb fraction (5.0–folds) was observed when soil was co-inoculated with Aspergillus flavus + Microbacterium paraoxydans compared to the control soil (un-inoculated soil) at 2000 mg Pb kg−1 concentration. Similarly, uptake results also indicated significantly higher Pb uptake in plants inoculated with A. flavus + M. paraoxydans. Soil microbial results indicated significant decrease in microbial health indicators and enzymatic activities with increasing Pb concentration and exposure time, as compared to control soil. A relatively severe decline was observed in soil respiration and dehydrogenase (DEH) activities by 2.8– and 2.5–folds, respectively at 2000 mg Pb kg−1 of soil. The optimized IPS was effective for restoring enzymatic activities in Pb contaminated soil and could be applied for sustainable restoration of Pb contaminated soil.

Heavy Metals Behavior in Soil/Plant System after Sewage Sludge Application

One of the possibilities of removing heavy metals (HMs) from soil is the use of phytoremediation techniques supported with biosolids, which also allow for their disposal. Therefore, the objective of the research was the determination of the sewage sludge suitability after its application to urban soil in order to increase the phytoremediation efficiency of contaminated soil. A field experiment was established on lawns in Białystok (Poland) in two locations with different traffic. The research plots were fertilized with sludge in doses of 14.5 t DM/ha and 29 t DM/ha. A mixture of lawn grasses was sown on the prepared plots. During two years of experiment soil/plant samples were collected, and pH, organic matter, dehydrogenase and catalase activity (soil), the total content of Cd, Cr, Cu, Mo, Ni, Pb, Zn, and Hg (soil/plant), and their fractions (soil) were determined. The HMs in soil were present mainly in residual and reducible fractions. Zn had the highest share in acid-soluble fractions (17–45%). The efficiency of urban soil phytoremediation was determined by the calculation of bioconcentration (BCF) and translocation (TF) factors. The highest values for BCF and TF were obtained for Mo (1.97 and 1.99, respectively). In the presented study, sludge amendment caused an immobilization of heavy metals.

Short Rotation Intensive Culture of Willow, Spent Mushroom Substrate and Ramial Chipped Wood for Bioremediation of a Contaminated Site Used for Land Farming Activities of a Former Petrochemical Plant.

The aim of this study was to investigate the bioremediation impacts of willows grown in short rotation intensive culture (SRIC) and supplemented or not with spent mushroom substrate (SMS) and ramial chipped wood (RCW). Results did not show that SMS significantly improved either biomass production or phytoremediation efficiency. After the three growing seasons, RCW-amended S. miyabeana accumulated significantly more Zn in the shoots, and greater increases of some PAHs were found in the soil of RCW-amended plots than in the soil of the two other ground cover treatments’ plots. Significantly higher Cd concentrations were found in the shoots of cultivar ‘SX61’. The results suggest that ‘SX61’ have reduced the natural attenuation of C10-C50 that occurred in the unvegetated control plots. The presence of willows also tended to increase the total soil concentrations of PCBs. Furthermore, we found that many contaminant concentrations were subject to seasonal oscillations, showing average increases throughout the whole experimental site after a growing period, while showing significantly different variations, such as lesser increases or even decreases, after a dormant period. These observations suggest that contaminants may have leached or degraded faster in untreated conditions, and conversely to have mobilized towards trees through water flow driven by plant transpiration during growing seasons.

Cadmium subcellular distribution and chemical form in Festuca arundinacea in different intercropping systems during phytoremediation

Intercropping with Cicer arietinum L has been suggested to improve the Cd decontamination capacity of Festuca arundinacea. However, the mechanisms stimulating this effect have not been revealed. The current study was designed to evaluate the changes in the subcellular distribution and chemical forms of Cd in different leaf types of F. arundinacea intercropped with C. arietinum L under different schemes. The results indicated that more than half of the Cd was bound in the cell wall in plant organs under all planting schemes, showing that cell wall deposition is an important detoxication pathway for the metal. Relative to the monoculture scheme, coordinate and malposed intercropping schemes increased the Cd concentration deposited in the cytoplasm of below-ground tissues from 37.6% to 45.2% and 45.1%, respectively. Additionally, the proportion of inorganic and water-soluble Cd in the below-ground parts of F. arundinacea increased from 73.6% in the monoculture scheme to 80.6% and 84.7%, in the coordinate and malposed intercropping schemes, respectively. The results exhibited that intercropping schemes can activate the metal in below-ground tissues and move it to aerial parts. The present study revealed the promoting mechanism of intercropping schemes on the phytoremediation efficiency of F. arundinacea for Cd at a subcellular level.

Exogenous Melatonin Enhances Cd Tolerance and Phytoremediation Efficiency by Ameliorating Cd-Induced Stress in Oilseed Crops: A Review

Heavy metal pollution is of increasing global concern as it adversely impacts different spheres including pedosphere, hydrosphere, biosphere, and humansphere. Cadmium (Cd) contamination of agriculture soil has become a thoughtful challenge across the globe due to uncontrolled anthropogenic activities, limiting agricultural productivity and disturbing eco-environment sustainability. Sustainable mitigation strategies are, therefore, required for effective Cd decontamination. Biostimulation is a promising method to improve and stimulate life processes of plants in general and oilseed crops in particular, without posing threats to eco-environment sustainability and safer food production. Melatonin (N-acetyl-5-methoxytryptamine), a recognized pleiotropic molecule, has emerged as a research highlight regarding its role as an effective natural plant growth promoter, a broad spectrum antioxidant, and more specifically an efficient biostimulator to improve Cd-induced tolerance of plants for phytoremediation purposes and simultaneous biofuel production. This review provides a novel insight to understand the multifunctional role of melatonin in improving Cd phytoremediation capacity together with reducing phytotoxicity in oilseed crops, which was not previously assessed. Among oilseed crops, Brassicaceae spp. have unique stress adaptive mechanisms with exceptionally high Cd accumulating capabilities, apart from the diverse agri-horticultural importance. Interestingly, the discovery of dynamic approaches regarding melatonin application helped to better understand the basic mechanisms involved in melatonin-mediated responses against Cd stress in oilseed crops. Our review will provide a useful basis for the development of alternative strategies to genetically engineer low-Cd-content oilseed crops, with the aim of improving eco-friendly crop production and ensuring food safety. Furthermore, future researches will be supposed to provide more genetic evidences about Cd-induced melatonin regulation in higher plants.

Identification of a New Potential Cd-Accumulator Pterocypsela indica (L.) Shih.

Three experiments were conducted to investigate the Cd tolerance and accumulation ability of a forage grass, Pterocypsela indica. P. indica accumulated 31.40 and 69.68mg/kg Cd in roots and shoots, respectively, and plant biomass was unaffected by soil Cd as high as 50mg/kg. Cd pollution obviously increased the Cd content of the cell wall fraction and decreased that of the soluble fraction in plant roots, but had little effect on the subcellular Cd content in plant shoots. When soil was co-contaminated by 2.29mg/kg Cd, 526.83mg/kg Zn, and 595.38mg/kg Pb, P. indica accumulated 61.63mg/kg Cd, 4261.00mg/kg Zn, and 75.27mg/kg Pb in plant shoots. The results indicated that P. indica mainly detoxified Cd stress by improving the fixation of Cd on the cell wall of plant roots rather than shoots. P. indica is a potential Cd accumulator that has a high phytoremediation efficiency in Cd-Zn-contaminated soil.

Influence of nano-titanium dioxide particles (TiO2 NPs) on improving phytoremediation efficiency of As/Cu/Cd from copper mine wastewaters using Lemna minor

Phytoremediation technology is an appropriate and eco-friendly technique with high efficiency to reduce heavy metal hazards from a contaminated environment. This study analyzed the effects of individual titanium dioxide nano-particles (TiO2 NPs) and combined with EDTA (TiO2 NPs+ EDTA) on phytoremediation of arsenic (As), copper (Cu), and cadmium (Cd) from copper mine wastewater using Lemna minor. The experiments were exposed using different concentrations of TiO2 NPs (200 and 300 mg kg−1) and EDTA (2 g kg−1) in seven treatments during 10 days. The content of As, Cu, and Cd was measured in plant tissues to calculate the total metal extraction (Ct), bioaccumulation factor (BF), and removal efficiency (RE). The content of As and Cu in the plant showed that uptake depended upon TiO2 NP concentration, and the Ct, BF, and RE values were affected by concentration of TiO2 NPs in wastewater. Adding 200 mg kg−1 TiO2 NPs to mine wastewater significantly increased the plant biomass (66.5%), relative growth rate (42.2%), relative growth factor (33.9%), and tolerance index (39.2%) compared to the individual wastewater treatment. Adding 200 mg kg−1 TiO2 NPs enhanced the As content, Ct, and BF values to 382.5± 41.2 mg kg−1, 122.1± 17.9 μg plant−1, and 664.2±161.2, respectively, while the combined use of TiO2 NPs+ EDTA and individual application of EDTA significantly decreased As uptake compared with wastewater treatment. For As, the RE (54.7%) and total absorbed (1786 kg ha−1 year−1) reached the maximum values following the application of 300 mg kg−1 TiO2 NPs, which were 25.8% and 30.1% higher than the control wastewater treatment, respectively. Furthermore, the BF values in control wastewater treatment showed that L. minor was known as a hyper-accumulate plant for the Cu metal, whereas the Ct, RE, and BF values increased due to applying individual TiO2 NPs and combined TiO2 NPs+EDTA. These results suggest that using TiO2 NPs for phytoremediation of contaminated water is helpful in enhancing As accumulation, whereas the L. minor is also a useful plant for Cu accumulation.

Pb-Contaminated Soil from Quintero-Ventanas, Chile: Remediation Using Sarcocornia neei.

A phytoremediation process for lead (Pb) under laboratory conditions on contaminated soil from the Puchuncaví commune, Valparaíso Province, Chile, was carried out. It analyzed the phytoremediation potential of Sarcocornia neei (Lag.) M.A. Alonso and M.B. Crespo. The plants were propagated beforehand and extracted from the El Yali wetland, a RAMSAR 878 site in Valparaíso. Soil fertility and heavy metal concentration analyses of composite samples were conducted, complying with established protocols and standard methodology for chemical and metal analyses. These analyses were conducted in the Soil Analysis Laboratory of the Pontificia Universidad Católica de Valparaíso. The aim was to analyse not only the tissue of plants from both areas but also the soil to identify the changes in different conditions in which the plants live. To determine the type of inferential analysis to be performed, a normality test was applied; however, it was deemed unsuitable, and therefore, the contrasts were developed using nonparametric tests, particularly Wilcoxon. R project software was used in the tests, especially the RCommander package, together with the Jamovi free-license statistical spreadsheet application. The analyses results of the soil samples indicated high concentrations of heavy metals, predominantly Pb at a concentration of 77.97 mg/kg, acidic soil indicated by pH between 5.77 and 6.38, low levels of electrical conductivity, and the presence of organic matter. A phytoremediation efficiency of 99% on soil samples was achieved. Preliminary results were compared against international regulations on the concentration of metals in soil. The histological sections showed that individual plants probably adapted to their environmental conditions.

Evaluation of some chelating agents on phytoremediation efficiency of Amaranthus caudatus L. and Tagetes patula L. in soils contaminated with lead.

This study was designed to evaluate the possible effects of some chelating agents on phytoremediation efficiency and plant growth parameters of Amaranthus caudatus L. and Tagetes patula L. in soils contaminated with lead. The plant species were grown in pots and treated with lead nitrate and in combination with 2.5, 2.0 and 2.5mmol/kg of EDTA, SA and CA, respectively. The results showed that the highest accumulations of Pb (mg/kg) with 0.74 and 0.13 were found in the roots and stems of A. caudatus exposed to 400mg/kg Pb containing EDTA and SA, respectively. Moreover, the highest accumulation of Pb in the roots and stems of T. patula with 0.87 and 1.5mg/kg were observed in 400mg/kg Pb- contaminated soil containing SA. Although the results obtained showed that T. patula would have a better phytoextraction potential than A. caudatus, it should be noted that due to the Pb behavior in the soil and/or leaching of Pb from the soil columns during the irrigation period the low amounts of Pb absorption by the root and aerial parts of the plants compared to the added doses of Pb(NO3)2 solution to the soil samples, imply the studied plants haven't the adequate potential for phytoextraction of Pb from contaminated soils.

Plant-Soil-Microbiota Combination for the Removal of Total Petroleum Hydrocarbons (TPH): An In-Field Experiment.

The contamination of soil with total petroleum hydrocarbons (TPH) may result in dramatic consequences and needs great attention, as soil rehabilitation would need more effort from a sustainability perspective. However, there is still no known general method since the remediation technology is strictly site-specific. Adaptive biological system dynamics can play a key role in understanding and addressing the potential of situ-specific biological combinations for soil pollutants removal. The potential worst-case of TPH contamination reflects soil affected by heavy industrial activities, such as oil refineries. Therefore, the experimental trial was conducted on a 2,000 m2 area from a contaminated site located in northern Italy. We evaluated the remediation potential over time (270 days) assessing (i) the phytoremediation efficiency of two species of Poaceae (Festuca arundinacea Schreb. and Dactylis glomerata L.) and two species of Fabaceae (Medicago sativa L. and Lotus corniculatus L.) and (ii) the role of the indigenous bacteria flora and endo-mycorrhizae consortium addition in plant growth promotion. We also induced resistance to contamination stress in a field experiment. Thirty-three indigenous bacteria selected from the contaminated soils showed marked plant growth promotion. Moreover, functional metagenomics confirmed the metabolic capability of hydrocarbon-degrading microorganisms living in the polluted soil. Our data showed that soil enzymatic activities increased with hydrocarbon degradation rate after 60 days. Both Poaceae and Fabaceae resulted in remarkable remediation potential. Stress markers and antioxidant activity indicated that the selected plant species generally need some time to adapt to TPH stress. In conclusion, our evaluation implied both the rhizosphere effects and functional features of the plant and suggested that plants should (i) have marked tolerance to specific contaminants, (ii) be characterized by an extensive root system, and (iii) be susceptible to arbuscular mycorrhizal fungi (AMF) infection.

Complete genome sequence of plant growth-promoting and heavy metal-tolerant Enterobacter tabaci 4M9 (CCB-MBL 5004).

Enterobacter tabaci 4M9 (CCB-MBL 5004) was reported to have plant growth-promoting and heavy metal tolerance traits. It was able to tolerate more than 300 mg/L Cd, 600 mg/L As, and 500 mg/L Pb and still maintained the ability to produce plant growth-promoting substances under metal stress conditions. To explore the genetic basis of these beneficial traits, the complete genome sequencing of 4M9 was carried out using Pacific Bioscience (PacBio) sequencing technology. The complete genome consisted of one chromosome of 4,654,430 bp with a GC content of 54.6% and one plasmid of 51,135 bp with a GC content of 49.4%. Genome annotation revealed several genes involved in plant growth-promoting traits, including the production of siderophore, indole acetic acid, and 1-aminocyclopropane-1-carboxylate deaminase; solubilization of phosphate and potassium; and nitrogen metabolism. Similarly, genes involved in heavy metals (As, Co, Zn, Cu, Mn, Se, Cd, and Fe) tolerance were detected. These support its potential as a heavy metal-tolerant plant growth-promoting bacterium and a good genetic resource that can be employed to improve phytoremediation efficiency of heavy metal-contaminated soil via biotechnological techniques. This, to the best of our knowledge, is the first report on the complete genome sequence of heavy metal-tolerant plant growth-promoting E. tabaci.

Impacts of root pruning and magnetized water irrigation on the phytoremediation efficiency of Celosia argentea

Pot experiments were conducted to evaluate the effects of magnetized water irrigation (100 mT) and root cutting (three pruning intensities) on phytoremediation efficiency of Celosia argentea. In the absence of magnetic field treatment, low root cutting intensity increased the dry weight of the below-ground and aerial parts of C. argentea. Moderate and severe cutting intensities decreased the biomass yield of the plant roots by 11.3% and 31.0%, and increased the dry weight of aerial parts by 75.9% and 27.6%, respectively, alleviating the detrimental effects of these pruning treatments on the plant roots. In the presence of magnetic field treatment, 10% and 25% of pruning treatments increased the dry weight of plant roots by 52.1% and 33.8%, and 33% pruning treatment decreased it by 14.1%. Under both irrigation treatments, low and moderate root cutting strategies did not affect the take up of Cd by the plant roots, while severe cutting decreased it significantly. Enzyme activities decreased with the increment of pruning intensity, and magnetic field can alleviate the negative impact, increasing the capacity of the root pruned species to scavenge the excessive ROS induced by the accumulated Cd. The results showed that root pruning enhanced the phytoremediation efficiency of C. argentea, and this effect was enhanced when combined with magnetized water irrigation.

Potential of Salicylic Acid and Synthetic Surfactant on Anthracene and Fluoranthene Remediation by Impatiens Balsamina

Plant growth regulators and synthetic surfactants are choices for enhancing the efficiency of PAH phytoremediation. In this study, the use of salicylic acid alone, surfactant alone (Triton X-100 or Tween 80), or salicylic acid together with Triton X-100 or Tween 80 on anthracene and fluoranthene removal by Impatiens balsamina were investigated. On days 15 and 30 of the experiment, the spraying of salicylic acid as 0.01 mM and watering of 1X CMC of Triton X-100 or Tween 80 were performed. Then, the plant growth parameters and anthracene or fluoranthene remaining in the soil were analyzed on day 45 of the experiment. The results revealed that I. balsamina did not enhance anthracene (77.4 % remained) and fluoranthene (74.6 % remained) removal when compared with unplanted soil (63.8 % of anthracene and 70.0 % of fluoranthene remained). Salicylic acid spraying in combination with watering of Triton X-100 (47.1 % anthracene remained) or Tween 80 (59.7 % anthracene remained) enhanced anthracene removal in unplanted soil; however, enhanced fluoranthene removal was not observed. In planted soil, salicylic acid spraying alone, Tween 80 watering alone or salicylic acid spraying in combination with synthetic surfactant (Triton X-100 or Tween 80) watering slightly enhanced anthracene removal (54.9-58.0 % of anthracene remained) but not fluoranthene (67.9 - 81.9 % of fluoranthene remained). The results revealed that planting contaminated soil with I. balsamina was not suitable to stimulate anthracene and fluoranthene degradation in this study. Biostimulation of unplanted soil with synthetic surfactant and salicylic acid was suitable to stimulate the removal of anthracene from the soil.

Habitats, phytochemical metabolites and phytoremediation potential of Ranunculus sceleratus L.

Ranunculus sceleratus L. (Ranunculaceae) is an invasive alien widespread species commonly distributed in canals and drains banks. In Egypt, this plant exhibits extensive growth with occasional pure populations in the Nile Delta region. This study aimed to address the drivers for R. sceleratus abundance, phytochemical composition, and phytoremediation efficiency. The average abundance of R. sceleratus within 60 stands of 25 m2 each was 47.9. The average root and stem lengths were 31.5 and 60.1 cm, respectively. The abundance of R. sceleratus was positively correlated with pH, electric conductivity, organic carbon, Fe, Mn, and Zn, while negatively correlated with total dissolved phosphorus, Cu, Co, Cd, and Pb. The shoot had the highest values of all bioactive-metabolites, where phenols, flavonoids, tannins, alkaloids and saponins were recorded 23.16, 5.11, 14.78, 6.34 and 18.50 mg kg-1 dry weight, respectively. R. sceleratus had shoot and root bioaccumulation factors (BF) in the following orders: Cd&gt; Ni&gt; Cu&gt; Pb&gt; Zn&gt; Fe&gt; Mn&gt; Co. R. sceleratus had BFshoot value of more than one for Ni, Cu, and Pb, while BFroot was greater than one for Cd, Ni, Cu, Pb, Zn, and Fe. Nevertheless, the translocation factor (TF) for all heavy metals were lower than one. Accordingly, R. sceleratus is a candidate for phytostabilization and/or phytoextraction tool for the most investigated heavy metals.

The role of Cyperus alopecuroides Rottb. sedge in monitoring water pollution in contaminated wetlands in Egypt: a phytoremediation approach.

Many macrophytes have heavy metal phytoremediation potential from contaminated watercourses. Therefore, the present study investigated the seasonal potential of the sedge plant Cyperus alopecuroides to remediate heavy metals from contaminated water bodies. Water, sediment, and plant samples were collected from four contaminated watercourses and the uncontaminated Nile River. Summer was the blooming season of C. alopecuroides with the highest shoot density, leaf size, fresh production, and dry biomass, while winter represented the lowest growth season. The photosynthetic pigments were distinctly decreased in plants growing in contaminated compared to the uncontaminated sites. Plant roots accumulated concentrations of all measured heavy metals, except Ni, Cu, Zn, and Pb, more significant than the shoot. The maximum concentrations of Al, Ni, and Pb were recorded during spring, while the highest Cd, Cr, Fe, and Mn were recorded during summer. The bioconcentration factor (BCF) of all investigated metals (except Al) was > 1, while the translocation factor (TF) of all elements (except Pb) was ˂1. These results indicated the capability of C. alopecuroides for metal phytostabilization and considered the target species a powerful phytoremediator for monitoring water pollution in contaminated wetlands. In this context, the above- and belowground parts of C. alopecuroides should be harvested in summer for efficient phytoremediation.

The Addition of Exogenous Low-Molecular-Weight Organic Acids Improved the Efficiency of Phytoremediation by &lt;i&gt;Bidens Pilosa&lt;/i&gt; L. In Cd-Contaminated Soil

The Addition of Exogenous Low-Molecular-Weight Organic Acids Improved the Efficiency of Phytoremediation by &lt;i&gt;Bidens Pilosa&lt;/i&gt; L. In Cd-Contaminated Soil

Enhanced technology of phytoremediation

The enhanced technology of phytoremediation has the advantages of low treatment cost, good purification effect, low environmental risk and environmental aesthetics. However, some hyperaccumulators grow slowly and their biomass is generally low; the activity of heavy metals in the soil is very low; the roots of plants are distributed in the surface of the soil, and the remediation effect of deep soil is poor; the nutrients of the soil to be repaired are seriously insufficient. It is necessary to take a series of strengthening measures to improve the efficiency of phytoremediation. The strengthening technologies of phytoremediation include chemical strengthening, microbial strengthening, animal strengthening, carbon dioxide strengthening, agronomic and management measures strengthening, etc.