Phytoremediation Of Metals Research Articles

Effect of Synthetic and Organic Chelators Application on Copper Phytoextraction by Calendula Officinalis L.

Background: Using ornamental plants for phytoremediation of Heavy Metals (HMs) in soil environments has been grown due to its cost-effectiveness and ease of use in urban environments. The aim of this study was to assess the potential use of Calendula officinalis for soil Copper (Cu) phytoremediation in the presence of different types of chelating agents (Ethylene Diamine Tetra-Acetic Acid (EDTA), Citric acid (CIT), and Tartaric Acids (TAR)) at different levels of Cu in a calcareous soil. Methods: To investigate the effects of stress caused by the use of chelating agents on biochemical changes of C. officinalis, the activity of some antioxidants of C. officinalis (Superoxide Dismutase (SOD), Catalase (CAT), Ascorbate Peroxidase (APX), Peroxidase (POD), and Polyphenol Oxidase (PPO)) was evaluated. Results: As results, C. officinalis showed an increase in shoot and root Cu concentration in the presence of all chelating agents compared to the control. The highest accumulation of Cu in the root/shoot was observed in EDTA-treated plants. However, an increased Cu level in plant parts (due to consuming of EDTA) was corresponded to lower dry weight in shoot and root; higher H2O2 and malondialdehyde (MDA) contents, and antioxidant activity (APX, PPO, CAT, SOD, and POD) in plants compared to the control treatment. On the contrary, the application of CIT and TAR primarily increased shoot and root dry weight and Cu concentration. Conclusion: Generally, the results of this study could be suggested that plants possess a well-organized resistance mechanism against oxidative stress caused by using of CIT and TAR.

Application potential of Chrysopogon zizanioides (L.) Roberty for the remediation of red mud-treated soil: an analysis via determining alterations in essential oil content and composition

The study was undertaken to determine the effects of different red mud treatments (0, 5, 10, and 15% w/w) in sewage-sludge amended soil (soil:sludge:2:1 w/w) on quantity, quality, and safety of essential oil extracted from the roots of Chrysopogon zizanioides (vetiver), when used for the phytoremediation of red mud. Garden soil without red mud and sewage-sludge served as control and there were 10 replicates for each treatment. Essential oil content in roots increased under all soil treatments except maximum red mud addition in sludge-amended soil compared to the control. Gas chromatography and mass spectroscopic analysis of oil revealed that 36, 35, 33, and 31 compounds contributed nearly 87.7, 90, 92.1, and 87% of total volatiles under 0, 5, 10, and 15% red mud treatments, respectively. Contents of rosifoliol, α-muurolol, farnesol, γ-costol, isovalencene, and vetivone increased, while selina-6-en-ol, cadin-4-en-10-ol, vetiselinenol, and aristolone decreased with increasing red mud treatments. In essential oil, contents of metals were within the safe limits for food by Food Safety and Standard Authority of India. The study insinuate utilization of 5 and 10% red mud in sludge-amended soil for improved quantity and quality of essential oil, without any metal contamination coupled with enhanced phytoremediation potential of vetiver. Novelty statement The present study is of significant importance because phytoremediation of metals in red mud using essential oil-bearing plants such as Chrysopogon zizanioides (commonly known as vetiver) is a potential alternative for on-site management of the waste in most economical and sustainable way. Vetiver is a potential metal tolerant plant with high economic value; therefore the present study was accomplished to evaluate the impacts of metals in red mud on essential oil content and composition, used for remediation and stabilization of dumps. Novelty of the study is that, it aimed to utilize red mud along with sewage-sludge to cultivate vetiver which offers twin benefits, i.e. phytoremediation of metals in red mud coupled with improved quantity and quality of high valued essential oil without metal contamination.

Effects of co-pyrolysis of heavy metal contaminated biomass with magnesium carbonate on heavy metal deportment and pyrolytic product properties

Vegetation has successfully been used for phytoremediation of heavy metal(loid) contaminated soils. Previous works found that the metal(loid)-enriched biomass can be converted into biofuels through pyrolysis. However, the potential emission of metal(loid)s at higher pyrolysis temperatures, the leaching potential of minerals in chars, and the quality of the products needs further consideration. In this work, the metal(loid)-enriched biomass was engineered by pre-mixing with magnesium carbonate to study the effect on pyrolytic product properties and metal(loid) deportment. Heavy metal contaminated mangrove grown in a land contaminated with a lead–zinc smelter slags was used as the biomass. The biomass and magnesium carbonate mixture as the feedstock was subjected to pyrolysis at temperatures from 300 to 900 °C under the heating rate of 10 °C/min. Results showed that the feedstock mainly decomposed at temperatures between 176 and 575 °C. Amongst the 10 studied metal(loid)s in this work, most elements exhibited more than 70% of elemental recovery in chars at pyrolysis temperatures up to 700 °C. Pyrolysis also enhanced heavy metal stability in chars produced at temperatures above 300 °C. This study indicated that co-pyrolysis of heavy metal contaminated biomass with magnesium carbonate enabled the pyrolysis temperature up to 700 °C with minimal environmental risks, providing a safe and value-added way of phytoremediation residual management.

Fungal and metabolome diversity of the rhizosphere and endosphere of Phragmites australis in an AMD-polluted environment

Symbiotic associations with rhizospheric microbial communities coupled with the production of metabolites are key adaptive mechanisms by metallophytes to overcome metal stress. However, little is known about pseudometallophyte Phragmites australis interactions with fungal community despite commonly being applied in wetland phytoremediation of acid mine drainage (AMD). In this study, fungal community diversity and metabolomes production by rhizosphere and root endosphere of P. australis growing under three different AMD pollution gradient were analyzed. Our results highlight the following: 1) Ascomycota and Basidiomycota were dominant phyla, but the diversity and richness of taxa were lower within AMD sites with Penicillium, Candida, Saccharomycetales, Vishniacozyma, Trichoderma, Didymellaceae, and Cladosporium being enriched in the root endosphere and rhizosphere in AMD sites than non-AMD site; 2) non-metric multidimensional scaling (NMDS) of 73 metabolomes revealed spatially defined metabolite exudation by distinct root parts (rhizosphere vs endosphere) rather than AMD sites, with significant variability occurring within the rhizosphere correlating to pH, TDS, Fe, Cr, Cu and Zn content changes; 3) canonical correspondence analysis (CCA) confirmed specific rhizospheric fungal taxonomic changes are driven by pH, TDS, heavy metals, and stress-related metabolomes produced. This is the first report that gives a snapshot on the complex endophytic and rhizospheric fungal community structure and metabolites perturbations that may be key in the adaptability and metal phytoremediation by P. australis under AMD environment.

Phytoremediation of Heavy Metals in Tropical Soils an Overview

The geomorphological characteristics of the materials inherent in tropical soils, in addition to the excessive use of fertilizers and pesticides, industrial waste and residues, and novel pollutants derived from emerging new technologies such as nanomaterials, affect the functionality and resilience of the soil-microorganism-plant ecosystem; impacting phytoremediation processes and increasing the risk of heavy metal transfer into the food chain. The aim of this review is to provide a general overview of phytoremediation in tropical soils, placing special emphasis on the factors that affect this process, such as nanoagrochemicals, and highlighting the value of biodiversity among plant species that have the potential to grow and develop in soils impacted by heavy metals, as a useful resource upon which to base further research.

Low Molecular Weight Organic Acids Increase Cd Accumulation in Sunflowers through Increasing Cd Bioavailability and Reducing Cd Toxicity to Plants

The use of low molecular weight organic acids (LMWOAs) for the phytoremediation of heavy metals has become a promising technique. We chose five kinds of organic acids (oxalic acid (OA), acetic acid (AA), tartaric acid (TA), malic acid (MA), and citric acid (CA)) with six application rates (1, 2, 3, 4, 5, and 6 mmol/kg) and planted sunflowers (Helianthus annuus L.) in Cd-polluted soil to study the efficiency of the phytoremediation of Cd and the degree of Cd toxicity to plants. Treatment with no acid application served as the control (CK). We analyzed the plant height dry matter and the Cd and nonprotein sulfhydryl (NPT) contents in the soil and plant tissues. OA, AA, TA, MA, and CA increased plant heights by 17.6–47.40%, 21.25–39.17%, 12.5–35.52, 5.10–30.50%, and 16.15–49.17%, respectively; shoot biomass of the sunflowers was increased except with MA. NPT decreased under LMWOA application, which, in the roots, increased with the increase in root Cd under LMWOA treatment; however, there was no obvious relationship in the stems and leaves. The composition of Cd in the soil changed significantly under the LMWOA treatments compared to the CK, and the changes in carbonate Cd and Fe-Mn oxide Cd were the most prominent. The plant Cd accumulation of OA, AA, TA, MA, and CA increased by 43.31%, 55.25%, 48.69%, 0.52%, and 32.94%, respectively, and the increase in root Cd content and shoot dry matter quality promoted the increase in Cd accumulation. The LMWOAs were more likely to affect the phytoremediation of Cd by changing total P (TP) rather than total N (TN).

Nickel tolerance and biosorption potential of rhizobia associated with horse gram [Macrotyloma uniflorum (Lam.) Verdc.

The rhizobia isolated from root nodules of horse gram were screened for nickel (Ni) tolerance in vitro. The strain HGR-4 could tolerate 1000 µg g−1 of Ni. It was also observed that horse gram plants associated with HGR-4 have shown Ni stress tolerance in Ni amended soils up to a concentration of 100 µg g−1. In another experiment, the plants associated with HGR-4 have shown higher nodulation, nitrogen level, and leghaemoglobin content at 80 µg g−1 of Ni than control plants without HGR-4 inoculation. Analysis of biosorption potential of Ni in horse gram plants inoculated by the strain HGR-4 was done using atomic absorption spectroscopy revealed maximum biosorption in bacterial root nodules. Besides, there was a reduction in the content of the heavy metal in the soil samples which demonstrates a fair amount of heavy metal extraction and accumulation of Ni by rhizobia associated root nodules of the horse gram. This study demonstrates that the strain HGR-4 (GQ483457 Rhizobium sp. ATCC BAA-2335) could be a potential source for phytoextraction of Ni contaminated soils upon its association with horse gram. The study could be of use in phytoremediation of metal (Ni) contaminated soils in the future. Novelty statement: The phytoremediation of nickel (Ni) using of rhizobia associated with horse gram remains unevaluated till now. Horse gram associated with rhizobia could produce nodules and fix nitrogen even in Ni amended soils. The biosorption potential of the rhizobial strains was analyzed from both root nodules and soil. These findings imply that horse gram plants associated with these rhizobial strains could be used to remediate Ni metal in contaminated soils.

Rhizobacteria associated with Miscanthus x giganteus improve metal accumulation and plant growth in the flotation tailings

Flotation tailings represent an extremely unfriendly substrate for plant colonization due to toxic metal concentrations and marked macronutrient deficiencies. The perennial grass Miscanthus x giganteus J.M.Greef & Deuter ex Hodk. & Renvoize was successfully cultivated in this infertile substrate for two years. Our aim was to identify composition of its rhizosphere bacterial community and to analyze the effects of the selected rhizobacteria on plant growth, root development, metal and P uptake. Using the cultivation-dependent method, 75 isolates were collected from the rhizosphere and six rhizobacterial strains were selected for further characterization based on morphological and biochemical differences. The plant rhizomes were inoculated with the consortium of rhizobacteria and cultivated in the flotation tailings substrate. Detected bacterial strains were characterized as metal-resistant and plant growth-promoting rhizobacteria (PGPR) because of their metal tolerance (NiCl2, Pb(C2H3O2)2, CuSO4, NaAsO2, MnCl2) and some or all of the plant growth-promoting (PGP) properties (indole-3-acetic acid and siderophore production, 1-aminocyclopropane-1-carboxylic acid deaminase activity and phosphate solubilization). PGPR mitigated the negative effects of high metal concentrations and macronutrient deficiency as shown by stimulated lateral roots development, increased root hair length, plant below and above ground biomass yield, higher plant P uptake and metal accumulation rate. The isolated PGPR strains could be used in PGP-bacteria assisted phytoremediation of flotation tailings and metal polluted soils by M. x giganteus. Their PGP effects on various metal-tolerant target plant species in the respective substrate remain to be verified.

Phytoremediation of heavy metals contaminated water and soils from artisanal mining enclave using Heliconia psittacorum

The activities of artisanal mining prevalent in most of Ghana has immensely contributed to the pollution of heavy metals and metalloids in both water and soils. This has resulted in the contraction of diseases associated with the ingestion of these pollutants. Aquatic plants have been recognised to be cost-effective and efficient means to remediate these pollutants from the environment. This study employed the use of Heliconia psittacorum in remediating soils polluted with heavy metals mercury (Hg), arsenic (As), cadmium (Cd) and lead (Pb). The remediation of these pollutants by H. psittacorum from polluted soil was studied in a greenhouse environment where the plants were grown. The irrigation of the plant was done with 10 ppm each of the heavy metals and metalloid. The roots and shoots of the plant were analysed of the number of heavy metals and metalloid absorbed by the plant after specific periods. There was high bio-absorption rate of As, Hg and Cd by H. psittacorum when each of the heavy metals/metalloids were the only contaminant in water as well as when all the four contaminants were together in the water. This means that the macrophyte can remediate As, Hg and Cd in soil and water. However, in the situation where the contaminants were paired in solution, there were synergistic effects on the metals uptake by the macrophytes, resulting in a low bio-absorption rate. This result indicates the fact that H. psittacorum can be used as one of the costs effective and green technology in remediating heavy metal contaminated soil/water.

Tolerance Mechanisms of the Aromatic and Medicinal Plant Salvia sclarea L. to Excess Zinc.

In recent years, due to the development of industrial and agricultural production, heavy metal contamination has attracted increasing attention. Aromatic and medicinal plant Salvia sclarea L. (clary sage) is classified to zinc (Zn) accumulators and considered as a potential plant for the phytoremediation of heavy metal polluted soils. In this study, an adaptation of clary sage to 900 µM (excess) Zn exposure for eight days in a hydroponic culture was investigated. The tolerance mechanisms under excess Zn exposure were assessed by evaluating changes in the nutrient uptake, leaf pigment and phenolic content, photosynthetic activity and leaf structural characteristics. The uptake and the distribution of Zn, as well as some essential elements such as: Ca, Mg, Fe, Mn and Cu, were examined by inductively coupled plasma mass spectrometry. The results revealed that Salvia sclarea is a Zn-accumulator plant that tolerates significantly high toxic levels of Zn in the leaves by increasing the leaf contents of Fe, Ca and Mn ions to protect the photosynthetic function and to stimulate the photosystem I (PSI) and photosystem II (PSII) activities. The exposure of clary sage to excess Zn significantly increased the synthesis of total phenolics and anthocyanins in the leaves; these play an important role in Zn detoxification and protection against oxidative stress. The lipid peroxidation and electrolyte leakage in leaves, used as clear indicators for heavy metal damage, were slightly increased. All these data highlight that Salvia sclarea is an economically interesting plant for the phytoextraction and/or phytostabilization of Zn-contaminated soils.

Physiological resistance of Sasa argenteostriata (Regel) E.G. Camus in response to high-concentration soil Pb stress

Dwarf bamboo Sasa argenteostriata (Regel) E.G. Camus has previously been considered as potential plant for metal phytoremediation. However, the dynamic responses and correlations among physiological resistances to high-concentration Pb exposure have not been described to date. This study conducted four Pb treatments (0, 1500, 3000, and 4500 mg kg–1) to examine the physiological resistance responses at days 7, 14, and 21. The findings showed that S. argenteostriata can regulate both the enzymatic system and the nonenzymatic system to synergistically overcome Pb damage. In addition, a significant positive correlation was found between enzymes and nonenzymatic substances, which were particularly apparent with regard to the superoxide dismutase (SOD) activities with phytochelatins (PCs) levels, peroxidase (POD), and glutathione reductase (GR) activities with glutathione (GSH) levels, as well as catalase (CAT) and ascorbate peroxidase (APX) activities with soluble protein (SP) levels. Furthermore, Pb concentration was the main factor that induced the physiological responses of S. argenteostriata to Pb stress. The antioxidant enzyme system and the AsA–GSH cycle were dominant resistance mechanisms under 1500 mg kg–1 Pb. AsA–GSH cycle and plant cell chelation were dominant resistance mechanisms under 3000 mg kg–1 Pb. Antioxidant enzymes and plant cell chelation were dominant resistance mechanisms under 4500 mg kg–1 Pb. This study provides comprehensive evidence regarding how both enzymatic and nonenzymatic systems of S. argenteostriata cooperate to alleviate the high-concentration soil Pb stress. The results highlight the environmental remediation potential of this species for Pb-contaminated media.

Are endophytes essential partners for plants and what are the prospects for metal phytoremediation?

Phytoremediation of soil contaminated by trace elements is a technology using plants and microorganisms to sequester, inactivate, or extract contaminants from the soil. The assemblage formed by the partnership between plants and microorganisms is referred to as the plant holobiont concept. Among holobiont microorganisms, endophytes are associated with the plant at its earliest growth stage and are localized inside plant tissues. While plant tissues shelter endophytic microbial communities, mutualistic endophytes have shown a potential for plant growth promotion that will deeply and durably benefit the plant holobiont. In this review, we describe the state-of-the-art knowledge of the endophytes’ role in plant growth promotion and the prospects for phytoremediation technologies. Mutualistic symbionts have been demonstrated to improve plant growth, germination and yield. Indeed, they improve plant nutrition, increase plant resistance to bio-aggressors and stimulate plant metabolite productions. Research has shown that endophytes improve plant performance especially under extreme conditions such as drought, nitrogen deficiency, salinity and exposition to metal phytotoxicity. Endophyte inoculation has shown potential for plant growth promotion and has increased metal translocation in hyperaccumulator shoots by mitigating stresses from contaminated and naturally metal-rich soils. Endophytes have demonstrated their potential to enhance the plant’s physiological status under metallic stress, the growth of both roots and shoots, as well as increasing metal uptake in the shoot biomass of a wide diversity of hyperaccumulating plants. Endophyte-assisted phytoremediation is a promising technology for the remediation of polluted or naturally metal-rich soils.

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.

Cadmium toxicity in Salvia sclarea L.: An integrative response of element uptake, oxidative stress markers, leaf structure and photosynthesis

The herbal plant Salvia sclarea L. (clary sage) is classified to cadmium (Cd) accumulators and considered as a potential plant for phytoremediation of heavy metal polluted soil. However, the effect of Cd only treatment on the function of the photosynthetic apparatus of S. sclarea, as well as the mechanisms involved in Cd tolerance have not yet been studied in detail. This study was conducted to examine the integrative responses of S. sclarea plants exposed to a high Cd supply (100 µM) for 3 and 8 days by investigating element nutrient uptake, oxidative stress markers, pigment composition, photosynthetic performance and leaf structure. Measurements of the functional activities of photosystem I (PSI, by P700 photooxidation), photosystem II (PSII, by chlorophyll fluorescence parameters), the oxygen-evolving complex (oxygen evolution by Joliot- and Clark-type electrodes), as well as the leaf pigment and phenolic contents, were used to evaluate the protective mechanisms of the photosynthetic apparatus under Cd stress. Data suggested that the molecular mechanisms included in the photosynthetic tolerance to Cd toxicity involve strongly increased phenolic and anthocyanin contents, as well as an increased non-photochemical quenching and accelerated cyclic electron transport around PSI up to 61%, which protect the function of the photosynthetic apparatus under stress. Furthermore, the tolerance of S. sclarea to Cd stress is also associated with increased accumulation of Fe in leaves by 25%. All the above, clearly suggest that S. sclarea plants employ several different mechanisms to protect the function of the photosynthetic apparatus against Cd stress, which are discussed here.

Advances in fungal-assisted phytoremediation of heavy metals: A review

Trace metals such as manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe) are essential for many biological processes in plant life cycles. However, in excess, they can be toxic and disrupt plant growth processes, which is economically undesirable for crop production. For this reason, processes such as homeostasis and transport control of these trace metals are of constant interest to scientists studying heavily contaminated habitats. Phytoremediation is a promising cleanup technology for soils polluted with heavy metals. However, this technique has some disadvantages, such as the slow growth rate of metal-accumulating plant species, low bioavailability of heavy metals, and long duration of remediation. Microbial-assisted phytoremediation is a promising strategy for hyperaccumulating, detoxifying, or remediating soil contaminants. Arbuscular mycorrhizal fungi (AMF) are found in association with almost all plants, contributing to their healthy performance and providing resistance against environmental stresses. They colonize plant roots and extend their hyphae to the rhizosphere region, assisting in mineral nutrient uptake and regulation of heavy metal acquisition. Endophytic fungi exist in every healthy plant tissue and provide enormous services to their host plants, including growth enhancement by nutrient acquisition, detoxification of heavy metals, secondary metabolite regulation, and enhancement of abiotic/biotic stress tolerance. The aim of the present work is to review the recent literature regarding the role of AMF and endophytic fungi in plant heavy metal tolerance in terms of its regulation in highly contaminated conditions.

The role of plant-associated bacteria in the phytoremediation of heavy metal contaminated soils

Soil heavy metal pollution is an important environmental problem threatening people’s health and sustainable economic development. Phytoremediation has become an important technology for the treatment of heavy metal contaminated soil with the characteristics of economy and environmental protection. This paper mainly analyzed the role of microbial community in heavy metal contaminated soil remediation process. Bacterias mainly strengthen the remediation effect of plants on heavy metal contaminated soil in two ways: first, bacterias have adsorption effect on heavy metals and reduce the toxicity of heavy metals to plants in soil; Two is to secrete organic acids and nutrients needed for plant growth to promote the absorption of heavy metals by hyperaccumulators.

Polluted Landfill adaptation into agricultural soil: heavy metal phytoremediation with Indian Black Mustard (Brassica Nigra) and Dolomitic Lime Fertilizer.

Bio-medical and electronic waste accumulation from industry and anthropogenic sources is deposited at landfill sites over the years, possessing waste degradation into heavy metal deposition in soil such as Cd, Ni, Pb, which is detrimental to the developing embryo development and affects respiratory function. The hyper-accumulator herb, such as Indian mustard ( Brassica Nigra), which was able to absorb heavy metals from the soil and water and wipe out soil after a period of time and disposed of it. Dolomitic Lime Fertilizer is a Inorganic compound derived from mixture of calcium carbonate (caco3) and magnesium carbonate (mgco3) are used for the sustained agriculture. The Extraction of heavy metals along with Dolomitic lime helps to increase the nitrogen fixation rate in soil and reduce the acidity nature of the soil also acts as a soil conditioners. They provide eco-friendly, cheap and renewable resource for the subsequent years. Phytoremediation of contaminated sites is requires low cost and more renewable compared to remediation strategies that involve removing polluted soil constituents.

Phytoremediation of Heavy Metals From Mixed Domestic Sewage Through Vertical- Flow Constructed Wetland Planted with Canna Indica and Acorus Calamus

The removal of contaminants from sewage wastewater through constructed wetlands is becoming increasingly popular worldwide. Constructed wetland (CW) is a man-made structure for wastewater treatment that uses natural processes associated with wetland vegetation, soils, and their associated microbial combinations. This study investigated the performance of experimental vertical flow constructed wetland (VFCW) cells to remove heavy metals (HMs) from primary treated sewage. The primary treated sewage was collected from the sewage treatment plant (STP) in the campus of Indira Gandhi National Tribal University, Amarkantak, India. Sewage wastewater samples were collected from all cells of the experimental VFCW and analyzed for four heavy metals (Zn, Fe, Cu, and Cr). The plant species results show that the removal efficiency of the Canna indica L. for Zn, Fe, Cu, and Cr was 95%, 92%, 96%, and 93 % and Acorus calamus L.were 89 %, 80 %, 91 %, and 47 % respectively. These macrophytes with the substrate (gravel and sand) have presented a wide range of tolerance to all the selected metals and therefore can be used for field-scale constructed wetland removal of heavy metals from sewage wastewater.

Metals uptake and translocation in salt marsh macrophytes, Porteresia sp. from Bangladesh coastal area

Studies from around the world have suggested salt marshes or coastal wetlands can be used as sites for phytoremediation of metals. However, no investigations have been conducted to assess metal accumulation and translocation capabilities of salt marsh macrophytes from Bangladesh coastal area. The aim of this study was to evaluate the uptake and translocation of eight metals, Fe, Zn, Mn, Cu, Co, Rb, Sr, and Pb in Porteresia sp. from the six salt marsh sites of Bangladesh. The leaf, shoots and root tissues of Porteresia sp. samples were analyzed for metals by using the energy-dispersive X-ray fluorescence (EDXRF). The decreasing trend of metal concentrations was, in roots; Fe > Mn > Pb > Cu > Zn > Sr > Rb > Co, in shoots; Mn >Fe > Cu > Pb > Zn > Sr > Rb > Co, in leaves; Fe > Mn > Cu > Pb > Zn > Rb > Sr > Co. Generally, roots of the Porteresia sp. showed high accumulation of the metals when compared to shoots and leaves suggesting relevant availability in the sediment. Pb was the only metal with concentrations significantly higher in the leaves and shoots than in the root. Except for Pb, bioaccumulation concentration factor (BCF) for all metals was lower than 1 in plant organs indicating poor absorption and bioavailability of metals. Higher value (>1) of BCF for Pb infers the species can potentially be used for Pb phytoremediation. However, the translocation factor (TF) confirmed the diversified mobility of the metals from below-ground part to above-ground parts for all the measured metals in the salt marsh species. Highest mobility was observed for Mn and Pb. But it was hard to find any regular trends among all the metals and all the sites.

Influence of Biochar Particle Size and Concentration on Pb and As Availability in Contaminated Mining Soil and Phytoremediation Potential of Poplar Assessed in a Mesocosm Experiment

Metal(loid)s found at many sites as a result of human activities induce contamination of ecosystems, which threatens the environment and public health. Several approaches can be used in order to reduce such negative impacts of pollutants, and among them, phytoremediation has gained attractive attention. The objective of the present study was to assess the capacity of Populus euramericana, Dorskamp cultivar, for the phytoremediation of metal(loid)s on a technosol (former mining site) highly contaminated mainly with Pb and As, and amended with biochars having different particle sizes. In a 46-day mesocosm glasshouse pot experiment, technosol was mixed at three ratios (0, 2, or 5% w/w) with four different hardwood-derived biochars (with various particle sizes) in order to study the biochar application rate and particle size effects on soil pore water (SPW) characteristics, on poplar growth, and on metal(loid) distribution and concentrations in the plant organs. The results showed that all biochars tested had a significant impact on several SPW physico-chemical parameters. Especially, biochar additions reduced available Pb concentrations but with no effect on As. In such conditions, Populus growth in amended technosol increased whatever rate and particle size of biochar used. Metal(loid) concentrations and repartition in plant organs showed the following: (1) for Pb, a higher root concentration with low aerial part translocation, which depended on biochar used, and (2) for As, mainly a root sequestration. We identified biochar with the finest particle size and combined with P. euramericana, Dorskamp, was the most suitable as remediation tools for Pb stabilization in post-mining contaminated soils.