Chelant-enhanced phytoextraction is one of the most promising technologies to remove heavy metals from soil. The key of the technology is to choose suitable additives in combination with a suitable plant. In the prese...Chelant-enhanced phytoextraction is one of the most promising technologies to remove heavy metals from soil. The key of the technology is to choose suitable additives in combination with a suitable plant. In the present study, laboratory batch experiment of metal solubilization, cress seeds germination were undertaken to investigate the metal-mobilizing capability and the phytotoxicity of organic additives, including ethylene diamine triacetic acid （EDTA）, citric acid, acetic acid, oxalic acid, glutamine and monosodium glutamate waste liquid （MGWL） from food industry. Experiments in pots were carried out to study the effects of the additives on Zn and Cd phytoextraction. Furthermore, a leaching experiment with lysimeter was performed to evaluate the environmental risks of additive-induced leaching to underground water. The results showed that EDTA had a strong mobilizing ability for Zn and Cd, followed by mixed reagent （MR） and MGWL. MGWL and acetic acid at 5 mmol equivalent per liter resulted in seed germination index less than 2%. Experiments in pots verified the phytotoxicity of acetic acid and MGWL. Addition of the mixed reagent at 6--10 mmol/kg significantly increased Zn phytoextraction by Thlaspi caerulescens. The same for EDTA and the mixed reagent at 10 mmol/kg by Sedum dfredii. But only mixed reagents could significantly increase Cd phytoextraction by the studied hyperaccumulators. This suggested that the strong chelant was not always the good agent to enhance phytoextraction. S. alfredii combined with 2--10 mmol/kg soil MR was preferred for phytoremediation of Cd/Zn contaminated soils in southern China, this could result in high phytoextraction of Cd/Zn and reduce the leaching risk to underground water than EDTA assisted phytoextration.展开更多
A mesocosm experiment was conducted to investigate whether plant coexistence affects cadmium （Cd） uptake by plant in contaminated soil. Tobacco （Nicotiana tabacum L. var. K326） and Japanese clover （Kummerowia str...A mesocosm experiment was conducted to investigate whether plant coexistence affects cadmium （Cd） uptake by plant in contaminated soil. Tobacco （Nicotiana tabacum L. var. K326） and Japanese clover （Kummerowia striata （Thunb.） Schindl.） were used. Cadmium was applied as 3CdSO4.SH2O in solution at three levels （0, 1, and 3 mg/kg soil） to simulate an unpolluted soil and soils that were slightly and moderately polluted with Cd. Tobacco （crop）, Japanese clover （non-crop）, and their combination were grown under each Cd treatment. Compared to monoculture and under all Cd treatments, co-planting with Japanese clover did not affect tobacco biomass but significantly increased Cd concentration in all tobacco tissues and enhanced Cd accumulation in tobacco shoots and roots. Compared to monoculture, co-planting reduced soil pH and increased Cd bioavailability. For tobacco, co-planting with Japanese clover increased the Cd bioconcentration factor （BCF） in Cd contaminated soil. Japanese clover also accumulated substantial quantities of Cd in shoots and roots. Thus, total Cd uptake by the plants was much greater with co-planting than with monoculture. The results suggested that phytoextraction can be effectively increased through tobacco co-planting with Japanese clover in mildly Cd-contaminated soil.展开更多
The ultimate purpose of phytoextraction is not only to remove heavy metals from soil but also to improve soil quality.Here, we evaluated how the joint effect of Streptomyces pactum(strain Act12) and inorganic(Hoagland...The ultimate purpose of phytoextraction is not only to remove heavy metals from soil but also to improve soil quality.Here, we evaluated how the joint effect of Streptomyces pactum(strain Act12) and inorganic(Hoagland’s solution) and organic(humic acid and peat) nutrients affected the phytoextraction practice of cadmium(Cd) and zinc(Zn) by potherb mustard, and the microbial community composition within rhizosphere was also investigated.The results indicated that the nutrients exerted synergistically with Act12, all increasing the plant biomass and Cd/Zn uptakes.The inoculation of Act12 alone significantly increased dehydrogenase activity of rhizosphere soil(P<0.05), while urease and alkaline phosphatase activities varied in different dosage of Act12.Combined application of microbial strain with nutrients increased enzymatic activities with the elevated dosage of Act12.16S ribosomal RNA high-throughput sequencing analysis revealed that Act12 inoculation reduced the diversity of rhizosphere bacteria.The Act12 and nutrients did not change dominant phyla i.e.,Proteobacteria, Bacteroidetes, Gemmatimonadetes, Actinobacteria and Acidobacteria, but their relative abundance differed among the treatments with: Peat>Act12>Humic acid >Hoagland’s solution.Comparatively, Sphingomonas replaced Thiobacillus as dominant genus after Act12 application.The increase in the Sphingomonas and Flavisolibacter abundances under Act12 and nutrients treatments gave rise to growth-promoting effect on plant.Our results revealed the important role for rhizosphere microbiota in mediating soil biochemical traits and plant growth, and our approach charted a path toward the development of Act12 combined with soil nutrients to enhance soil quality and phytoextraction efficiency in Cd/Zn-contaminated soils.展开更多
This paper will review the topic of phytoextraction,a major approach of phytoremediation,by clarifying the roles of hyperaccumulators,bio-mechanisms involved,issues regarding contaminant uptake,artificial chelation,ge...This paper will review the topic of phytoextraction,a major approach of phytoremediation,by clarifying the roles of hyperaccumulators,bio-mechanisms involved,issues regarding contaminant uptake,artificial chelation,genetic selection,and cultivation.The paper will also address the practical issues and the regulatory context of this emerging technology and briefly discuss avenues for future research.展开更多
The plant samples of Bidens pilosa were collected from a coal gangue vacant site and its surrounding area,located in central China,to study the remediation effect of the plant species on heavy metal(HM)contamination i...The plant samples of Bidens pilosa were collected from a coal gangue vacant site and its surrounding area,located in central China,to study the remediation effect of the plant species on heavy metal(HM)contamination in both natural and electrokinetic(EK)conditions.The analytical results showed that the effect of phytoextraction and bioconcentration on the heavy metals in the sample of the EK group is more significant than those in the other control group.Compared with the results of natural condition,under the EK condition the concentrations of cadmium(Cd),lead(Pb),copper(Cu)and zinc(Zn)in the stems and leaves of the Bidens pilosa increased to 0.40 mg/kg,4.23 mg/kg,7.27 mg/kg,830.24 mg/kg,respectively,with their increments of 292%,1731%,141%,2076%.For root samples,the Cd,Pb,Cu and Zn concentrations increased to 0.52 mg/kg,4.36 mg/kg,10.87 mg/kg,and 98.12 mg/kg and the increase rates were 1034%,140%,29%,and 181%,respectively.The phytoextraction efficiency of the Bidens pilosa was significantly higher than that of control group.The removal efficiency of Cd,Pb,Cu and Zn in soil increased to 26%,72%,27%,and 79%with the EK applied.In addition,the mechanism of HM migration,extraction and enrichment in Bidens pilosa under the EK condition was discussed.展开更多
Fungi Z4 and Z8, isolated from the heavy metal polluted soil, have strong resistance to Cd and Pb. The strains were identified on the base of their morphology and internal transcribed spacers(ITS) region. Pot experime...Fungi Z4 and Z8, isolated from the heavy metal polluted soil, have strong resistance to Cd and Pb. The strains were identified on the base of their morphology and internal transcribed spacers(ITS) region. Pot experiments were conducted to study the effect of two strains(Z4 and Z8) on the growth and accumulation of Cd and Pb of Guizhou oilseed rape. The results show that strains Z4 and Z8 belong to Mucor circinelloides and Mucor racemosus, respectively. The heights of Guizhou oilseed rape inoculated with strain Z8 increase by 47.90% than the control. The highest fresh mass is found in the plant with Z4/Z8, which is enhanced by160.81%. Pot experiments show that Z4/Z8 inoculums can accelerate accumulation of heavy metals in the plant. The contents of Cd and Pb are increased by 117.60% and 63.48%, respectively. Meanwhile, the heavy metal concentrations in potting soil with the two strains are found to be lower than those of the control, and the concentrations of Cd and Pb are decreased by 60.57% and 27.12%,respectively.展开更多
This study aims to assess the effective capacity of <i>Panicum</i><span> <i>maximum</i> </span>to accumulate cadmium (Cd), nickel (Ni) and lead (Pb). <i>P</i><span>...This study aims to assess the effective capacity of <i>Panicum</i><span> <i>maximum</i> </span>to accumulate cadmium (Cd), nickel (Ni) and lead (Pb). <i>P</i><span>. <i>maximum</i></span> observed in a greenhouse was subjected to 2 ppm of Cd, 50 ppm of Ni, 100 ppm of Pb contaminated soil and uncontaminated soil, </span></span><span><span><span style="font-family:"">for</span></span></span><span><span><span style="font-family:""> 120 days. Plant growth and biomass produced concentration of trace metals in soil and plant, bioaccumulation and transfer factors, location of potentially toxic elements in tissues and cells of plant ha</span></span></span><span><span><span style="font-family:"">ve</span></span></span><span><span><span style="font-family:""> been determined. Stem length and biomass produced by <i>P</i><span>. <i>maximum</i></span> were higher on the uncontaminated soil followed respectively by those of soil-contaminated by Pb, Cd and Ni. Bioaccumulation factors of trace metals were 8.93 (Pb), 8.47 (Ni) and 3.37 (Cd). Ni was more accumulated in shoot biomass (FT > 1), while Pb and Cd were concentrated in root biomass (FT </span></span></span><span><span><span style="font-family:""><</span></span></span><span><span><span style="font-family:""> 1). Pb is accumulated preferentially in endodermis (roots) and epidermis (leaves). As for Ni and Cd, they are concentrated in central cylinder of roots and in conductive bundles of leaves. At cellular level, Ni and Cd are mainly concentrated in intracellular compartments of leaves and roots, while Pb is strongly detected at cell walls.展开更多
Neptunia amplexicaulis is an herbaceous legume endemic to the Richmond area in central Queensland,Australia and is one of the strongest known Selenium hyperaccumulators on earth,showing significant potential to be uti...Neptunia amplexicaulis is an herbaceous legume endemic to the Richmond area in central Queensland,Australia and is one of the strongest known Selenium hyperaccumulators on earth,showing significant potential to be utilised in Se phytoextraction applications.Here a protocol was established for in vitro micropropagation of Se hyperaccumula-tor N.amplexicaulis using nodal segments from in vitro-germinated seedlings.Shoot multiplication was achieved on Murashige and Skoog(MS)basal media supplemented with various concentrations of 6-Benzylaminopurine(BA)(1.0,2.0,3.0 mg L^(−1))alone or in combination with low levels of Naphthaleneacetic acid(NAA)(0.1,0.2,0.3 mg L^(−1)),with 2.0 mg L^(−1) BA+0.2 mg L^(−1) NAA found to be most effective.Elongated shoots were rooted in vitro using NAA,with highest root induction rate of 30%observed at 0.2 mg L^(−1) NAA.About 95%of the in vitro rooted shoots survived acclimatization.Clonally propagated plantlets were dosed with selenate/selenite solution and assessed for Se tissue concentrations using Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AES)and found to retain their ability to hyperaccumulate.The protocol developed for this study has potential to be optimised for generating clonal plants of N.amplexicaulis for use in research and phytoextraction industry applications.展开更多
A greenhouse study was conducted on phytoextraction and accumulation of lead (Pb) and cadmium (Cd) from contaminated soil – water microcosms by the narrow-leaved cattail, Typha angustifolia. The plants were grown in ...A greenhouse study was conducted on phytoextraction and accumulation of lead (Pb) and cadmium (Cd) from contaminated soil – water microcosms by the narrow-leaved cattail, Typha angustifolia. The plants were grown in sandy loam soil containing 1,666 and 38.5 mg/L of Pb(NO3)2 and Cd(NO3)2 respectively. The trends of lead and cadmium by T. angustifolia for all soil – water microcosms suggested interaction effects as decreased soil lead concentrations and increased water cadmium concentrations over time. T. angustifolia expressed trends as increased biomass in all contaminated shoots and roots examined. Cadmium uptake in shoot and root biomass slightly decreased when lead was initially added to the soil but cadmium uptake in root biomass increased after 30 days. Data suggested an interaction between lead and cadmium and possible that lead uptake was inhibited when cadmium was present.展开更多
Phytoextraction has been introduced as a new technology to clean up soils contaminated with heavy metals as the use of conventional methods to clean up the soil is very expensive and destructive to the ecosystem. Howe...Phytoextraction has been introduced as a new technology to clean up soils contaminated with heavy metals as the use of conventional methods to clean up the soil is very expensive and destructive to the ecosystem. However, using plants to clean up contaminated soils takes a considerable period before the contaminants are removed from the soil by the plants. This has necessitated the use of amendments to enhance phytoextraction in order to shorten the period of contaminants removal by plants. In view of this, a pot experiment was conducted to study the effect of various aminopolycarboxylic acids (EDTA, EDDS, NTA dry and NTA liquid) and two commercial fertilizers which are Hortrilon? and Fetrilon? on their ability to solubilize Cd and Zn in contaminated soils. It was observed that the inducing effect of EDTA on the solubility of Cd and Zn persisted throughout the experimental period. Initially, EDDS enhanced the solubility Cd and Zn, however, its effect dissipated with time. The application of both NTA dry (powder) and NTA liquid had a significant effect on the solubility of Zn as a result of the formation of Zn-NTA soluble complexes. Hortrilon? and Fetrilon? solubilized significant concentrations of both Cd and Zn with Hortrilon? having the greatest inducing effect on the solubility of Cd and Zn.展开更多
This study aims to investigate the capacity of <i>Chrysopogon</i> <i>nigritanus</i> to accumulate As from contaminated soils<i>.</i><b> </b>The experiment was conducted ...This study aims to investigate the capacity of <i>Chrysopogon</i> <i>nigritanus</i> to accumulate As from contaminated soils<i>.</i><b> </b>The experiment was conducted in a greenhouse. <i>C.</i> <i>nigritanus</i> was subjected to uncontaminated soil and As contaminated soil (50 mg/kg, 100 mg/kg and 150 mg/kg of As), for 180 days. Plant growth and biomass produced, concentration of As in soil and plant, bioaccumulation and transfer factors, as the location of As in tissues and cells of the plant have been determined. Plant growth decreased significantly with increasing of soil As concentration. <i>C.</i> <i>nigritanus</i> accumulated more As in roots biomass. The highest bioaccumulation factor values were found in contaminated soil at 50 mg As/kg (As 50), then contaminated soil at 100 mg As/kg (As 100) and contaminated soil at 150 mg As/kg (As 150). As was essentially fixed to the intracellular compartment of the roots, stems and leaves. In roots tissues, As was mainly retained in the rhizodermis and the pericycle. While in stems tissues, As was preferentially accumulated in the conductive bundles. In the leaves, the final destination of As was epidermis tissues.展开更多
Escalating anthropogenic activities have caused heavy metal contamination in the environmental matrices.Due to their recalcitrant and toxic nature,their occurrence in high titers in the environment can threaten surviv...Escalating anthropogenic activities have caused heavy metal contamination in the environmental matrices.Due to their recalcitrant and toxic nature,their occurrence in high titers in the environment can threaten survival of biotic components.To take the edge off,remediation of metal-contaminated sites by phytoremediators that exhibit a potential to withstand heavy metal stress and quench harmful metals is considered an eco-sustainable approach.Despite the enormous potential,phytoremediation technique suffers a setback owing to high metal concentrations,occurrence of multiple pollutants,low plant biomass,and soil physicochemical status that affect plants at cellular and molecular levels,inducing morphological,physiological,and genetic alterations.Nevertheless,augmentation of soil with microorganisms can alleviate the challenge.A positive nexus between microbes,particularly plant growth-promoting microorganisms(PGPMs),and phytoremediators can prevent phytotoxicity and augment phytoremediation by employing strategies such as production of secondary metabolites,solubilization of phosphate,and synthesis of 1-aminocyclopropane-1-carboxylic acid(ACC)deaminase and phytohormones.Microbes can mediate tolerance in plants by fortifying their antioxidant machinery,which maintains redox homeostasis and alleviates metal-induced oxidative damage in the plants.Associated microbes can also activate stress-responsive genes in plants and abridge metal-induced toxic effects.An in-depth exploration of the mechanisms employed by plant-associated microbes to trigger tolerance in phytoremediators is crucial for improving their phytoremediation potential and real-world applications.The present article attempts to comprehensively review these mechanisms that eventually facilitate the development of improved/new technology for soil ecosystem restoration.展开更多
Soil metal pollution is a global issue due to its toxic nature affecting ecosystems and human health. This has become a concern since metals are non-biodegradable and toxic. Most of the reclamation methods currently u...Soil metal pollution is a global issue due to its toxic nature affecting ecosystems and human health. This has become a concern since metals are non-biodegradable and toxic. Most of the reclamation methods currently used for soils rely on the use of physical and chemical means, which tend to be very expensive and result in secondary environmental damage. However, microbe-aided phytoremediation is gaining attention as it is an eco-friendly, affordable, and technically advanced method to restore the ecosystem. It is essential to understand the complex interaction between plants and microbes. The primary function of plant growth-promoting bacteria (PGPB) is to stimulate plant development, aid in metal elimination, and reduce their bioavailability in the soil. These microbes regulate phytohormones, stimulate processes such as phytoextraction and phyto-stabilization, and improve the uptake of essential nutrients, such as nitrogen and phosphorus. PGPBs secrete a range of enzymes and chemicals, fix nitrogen, solubilize minerals, increase the bioavailability of nutrients under diverse biological environments with high salinities, excessive metal-contaminated soil, and organic pollutants, increase the soil fertility and help in the reclamation of agriculture and regenerate the native flora. The integration of CRISPR-Cas9 gene-editing technology with microbial-aided phytoremediation and the use of genetically modified microbes with nanomaterials further enhance the efficacy of the approaches in polluted environments for sustainable restoration of the soil.展开更多
Exogenous application of chelators towards enhancing heavy metals extraction efficiency of bioenergy crop has received considerable attention in recent time.However,little is known about optimal application rate,compa...Exogenous application of chelators towards enhancing heavy metals extraction efficiency of bioenergy crop has received considerable attention in recent time.However,little is known about optimal application rate,comparative evaluation of degradable versus non-degradable chelators and their impact on cadmium(Cd)speciation and uptake,physiological and biochemical activity of sweet sorghum grown under Cd stress.Four chelators namely,Nitrilotriacetic acid(NTA),tetrasodium N,N-diacetate(TDA),Ethylenediamine tetraacetic acid(EDTA),iminodisuccinic acid(IDA)and control(CK)were applied and compared at rates of 2,5,and 10 mmol kg^(-1) towards augmenting phytoextraction efficiency of sweet sorghum for Cd remediation in a screen house study.Results showed that sweet sorghum augmented with TDA significantly(P<0.05)increased biomass,enhanced Cd uptake and accumulation when compared to EDTA at application rate of 2-5 mmol kg1.TDA influenced Cd speciation via increasing acid-soluble,reducible,oxidizable,and residual fractions of Cd,thus increasing Cd bioavailability.NTA and TDA increased proline concentrations,antioxidant enzymes and net photosynthetic activity rate(Pn)comparably to EDTA in sweet sorghum,thus enhancing stress tolerance and stabilizing photosynthetic activities.Overall,exogenous application of degradable TDA at 2-5 mmol kg^(-1) could be recommended as replacement for non-degradable EDTA in a chelate assisted approach towards augmenting bioenergy crop for phytoremediation of Cd polluted soil.展开更多
Chelating agent is known as the enhancer for metal phytoextraction;however,there is still a lack of efficient and environmentally sustainable chelators.Here,lemon residue extraction(LRE),prepared from 11 kinds of frui...Chelating agent is known as the enhancer for metal phytoextraction;however,there is still a lack of efficient and environmentally sustainable chelators.Here,lemon residue extraction(LRE),prepared from 11 kinds of fruit wastes,was combined with N,N-bis(carboxymethyl)glutamic acid(GLDA),and tea saponin(T.S.)for the compounded plant-derived chelator(CPC),and their influences on Cd phytoextraction by the hyperaccumulator Sedum alfredii was evaluated.Among these fruits,the lemon residue extracted the most significant amount of Cd from the soil.The most effective CPC was at the volume ratio of three agents being 15:4:1(LRE:GLDA:T.S.).Compared with the deionized water,the solubility of three Cd minerals was increased by 85–256 times,and Cd speciation was substantially altered after CPC application.In the pot experiment,CPC addition caused evident increases in plant shoot biomass,Cd phytoextraction efficiency,and organic matter content compared with EDTA and nitrilotriacetic acid(NTA)application.CPC induced fewer changes in bacterial community composition compared with EDTA and had no pronounced influence on microbial biomass carbon and bacterialα-diversity,suggesting CPC had a subtle impact on the microbiological environments.Our study provides a theoretical base for the reutilization of fruit wastes and the development of environmental-friendly chelator that assists Cd phytoextraction.展开更多
Soil contaminated with heavy metals cadmium （Cd） and lead （Pb） is hard to be remediated. Phytoremediation may be a feasible method to remove toxic metals from soil, but there are few suitable plants which can hype...Soil contaminated with heavy metals cadmium （Cd） and lead （Pb） is hard to be remediated. Phytoremediation may be a feasible method to remove toxic metals from soil, but there are few suitable plants which can hyperaccumulate metals. In this study, Cd and Pb accumulation by four plants including sunflower （Helianthus annuus L.）, mustard （Brassicajuncea L.）, alfalfa （Medicago sativa L.）, ricinus （Ricinus communis L.） in hydroponic cultures was compared. Results showed that these plants could phytoextract heavy metals, the ability of accumulation differed with species, concentrations and categories of heavy metals. Values of BCF （bioconcentration factor） and TF （translocation factor） indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals. Changes on the biomass of plants, pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures. Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals, such as pH and Eh regulations, and so forth.展开更多
Metal contamination in the environment is a global concern due to its high toxicity to living organisms and its worldwide distribution. The principal goal of this review is to examine the current strategies and techno...Metal contamination in the environment is a global concern due to its high toxicity to living organisms and its worldwide distribution. The principal goal of this review is to examine the current strategies and technologies for the remediation of metal- contaminated soils by metal-accumulating plants and assess the roles of arbnscular mycorrhizal （AM） fungi in remediation of soils under hyperaccumulator or non-accumulator plants. The use of plants to remove metals from the environment or reduce the toxicity, known as phytoremediation, is an environmentally sustainable and low cost remediation technology. The mechanisms of the use of hyperaccumulator plants for phytoremediation included solubilization of the metal in the soil matrix, the plant uptake of the metal, detoxification/chelation and sequestration, and volatilization. Recently, some ecologists have found that phytoremediation with the aids of mycorrhizae can enhance efficiency in the removal of toxic metals. AM fungi can facilitate the survival of their host plants growing on metal-contaminated land by enhancing their nutrient acquisition, protecting them from the metal toxicity, absorbing metals, and also enhancing phytostabilization and phytoextraction. Such information may be useful for developing phytoremediation program at metal-contaminated sites.展开更多
A soil–plant biological system was developed from chromium（Cr） polluted soil treated by the compost-phytoremediation method. The transformation and migration of the Cr in this system is comprehensively studied in t...A soil–plant biological system was developed from chromium（Cr） polluted soil treated by the compost-phytoremediation method. The transformation and migration of the Cr in this system is comprehensively studied in this research. The results illustrated that the co-composting treatment can reduce the Cr availability from 39%（F1 was about 31% of total, F2 was about 8% of total） to less than 2% by stabilizing the Cr. However, herbaceous plants can accumulate the concentrations of Cr from 113.8 to 265.2 mg/kg in the two crops,even though the concentration of soluble Cr in the substrate soil was below 0.1 mg/L.Cr can be assimilated and easily transferred in the tissues of plants because the lowmolecular-weight organic-acids（LMWOAs） derived from the plant root increase the bioavailability of Cr. The amount of extracted Cr dramatically increased when the organic acids were substituted in this order： citric acid 〉 malic acid 〉 tartaric acid 〉 oxalic acid 〉acetic acid. On average the maximum（147.4 mg/kg） and the minimum（78.75 mg/kg） Cr were extracted by 20 mmol/L citric acid and acetic acid, respectively. The desorption of Cr in different acid solutions can be predicted by the pseudo second-order kinetics. The exchangeable Cr, carbonate-bound Cr, and residual Cr decreased, while Fe–Mn oxide bound Cr and organic bound Cr increased in the soil solid phase. According to the experimental results, the organic acids will promote the desorption and chelation processes of Cr, leading to the remobilization of Cr in the soil.展开更多
The growth of high biomass crops facilitated by optimal of agronomic practices has been considered as an alternative to phytoremediation of soils contaminated by heavy metals. A field trial was carded out to evaluate ...The growth of high biomass crops facilitated by optimal of agronomic practices has been considered as an alternative to phytoremediation of soils contaminated by heavy metals. A field trial was carded out to evaluate the phytoextraction efficiency of heavy metals by three varieties of sweet sorghum （Sorghum biocolor L.）, a high biomass energy plant. Ethylene diamine tetraacetate （EDTA）, ammonium nitrate （NH4NO3） and ammonium sulphate （（NH4）2SO4） were tested for their abilities to enhance the removal of heavy metals Pb, Cd, Zn, and Cu by sweet sorghum from a contaminated agricultural soil. Sorghum plants always achieved the greatest removal of Pb by leaves and the greatest removal of Cd, Zn and Cu by stems. There was no significant difference among the Keller, Rio and Mray varieties of sweet sorghums in accumulating heavy metals. EDTA treatment was more efficient than ammonium nitrate and ammonium sulphate in promoting Pb accumulation in sweet sorghum from the contaminated agricultural soil. The application of ammonium nitrate and ammonium sulphate increased the accumulation of both Zn and Cd in roots of sorghum plants. Results from this study suggest that cropping of sorghum plants facilitated by agronomic practices may be a sustainable technique for partial decontamination of heavy metal contaminated soils.展开更多
Phytoremediation is a valuable technology for mitigating soil contamination in agricultural lands,but phytoremediation without economic revenue is unfeasible for land owners and farmers.The use of crops with high biom...Phytoremediation is a valuable technology for mitigating soil contamination in agricultural lands,but phytoremediation without economic revenue is unfeasible for land owners and farmers.The use of crops with high biomass and bioenergy for phytoremediation is a unique strategy to derive supplementary benefits along with remediation activities.Sunflower(Helianthus annuus L.)is a high-biomass crop that can be used for the phytoremediation of polluted lands with additional advantages(biomass and oil).In this study,40 germplasms of sunflower were screened in field conditions for phytoremediation with the possibility for oil and meal production.The study was carried out to the physiological maturity stage.All studied germplasms mopped up substantial concentrations of Pb,with maximum amounts in shoot>root>seed respectively.The phytoextraction efficiency of the germplasm was assessed in terms of the Transfer factor(TF),Metal removal efficiency(MRE)and Metal extraction ratio(MER).Among all assessed criteria,GP.8585 was found to be most appropriate for restoring moderately Pb-contaminated soil accompanied with providing high biomass and high yield production.The Pb content in the oil of GP.8585 was below the Food safety standard of China,with 59.5% oleic acid and 32.1% linoleic acid.Moreover,amino acid analysis in meal illustrated significant differences among essential and nonessential amino acids.Glutamic acid was found in the highest percentage(22.4%),whereas cysteine in the lowest percentage(1.3%).Therefore,its efficient phytoextraction ability and good quality edible oil and meal production makes GP.8585 the most convenient sunflower germplasm for phytoremediation of moderately Pb-contaminated soil,with fringe benefits to farmers and landowners.展开更多
基金The Hi-Tech Research and Development Program (863) of China (No. 2001-AA-640501-3)French-Chinese Programme deRecherche Avancee (No. PRA E-03-02) the National Natural Science Foundation of China (No. 40571141)
文摘Chelant-enhanced phytoextraction is one of the most promising technologies to remove heavy metals from soil. The key of the technology is to choose suitable additives in combination with a suitable plant. In the present study, laboratory batch experiment of metal solubilization, cress seeds germination were undertaken to investigate the metal-mobilizing capability and the phytotoxicity of organic additives, including ethylene diamine triacetic acid （EDTA）, citric acid, acetic acid, oxalic acid, glutamine and monosodium glutamate waste liquid （MGWL） from food industry. Experiments in pots were carried out to study the effects of the additives on Zn and Cd phytoextraction. Furthermore, a leaching experiment with lysimeter was performed to evaluate the environmental risks of additive-induced leaching to underground water. The results showed that EDTA had a strong mobilizing ability for Zn and Cd, followed by mixed reagent （MR） and MGWL. MGWL and acetic acid at 5 mmol equivalent per liter resulted in seed germination index less than 2%. Experiments in pots verified the phytotoxicity of acetic acid and MGWL. Addition of the mixed reagent at 6--10 mmol/kg significantly increased Zn phytoextraction by Thlaspi caerulescens. The same for EDTA and the mixed reagent at 10 mmol/kg by Sedum dfredii. But only mixed reagents could significantly increase Cd phytoextraction by the studied hyperaccumulators. This suggested that the strong chelant was not always the good agent to enhance phytoextraction. S. alfredii combined with 2--10 mmol/kg soil MR was preferred for phytoremediation of Cd/Zn contaminated soils in southern China, this could result in high phytoextraction of Cd/Zn and reduce the leaching risk to underground water than EDTA assisted phytoextration.
基金supported by the Science and Technology Department of Zhejiang Province (No. 2007C13063)the National Natural Science Foundation of China (No30970477)+1 种基金the Natural Science Foundation of Zhejiang Province (No. Y307418)the Key Laboratory of Ministry of Agriculture,China (No. KYJD09021)
文摘A mesocosm experiment was conducted to investigate whether plant coexistence affects cadmium （Cd） uptake by plant in contaminated soil. Tobacco （Nicotiana tabacum L. var. K326） and Japanese clover （Kummerowia striata （Thunb.） Schindl.） were used. Cadmium was applied as 3CdSO4.SH2O in solution at three levels （0, 1, and 3 mg/kg soil） to simulate an unpolluted soil and soils that were slightly and moderately polluted with Cd. Tobacco （crop）, Japanese clover （non-crop）, and their combination were grown under each Cd treatment. Compared to monoculture and under all Cd treatments, co-planting with Japanese clover did not affect tobacco biomass but significantly increased Cd concentration in all tobacco tissues and enhanced Cd accumulation in tobacco shoots and roots. Compared to monoculture, co-planting reduced soil pH and increased Cd bioavailability. For tobacco, co-planting with Japanese clover increased the Cd bioconcentration factor （BCF） in Cd contaminated soil. Japanese clover also accumulated substantial quantities of Cd in shoots and roots. Thus, total Cd uptake by the plants was much greater with co-planting than with monoculture. The results suggested that phytoextraction can be effectively increased through tobacco co-planting with Japanese clover in mildly Cd-contaminated soil.
基金supported by the Fundamental Research Funds for the Central Universities of China (Nos. 3102019JC007, G2021KY0601)。
文摘The ultimate purpose of phytoextraction is not only to remove heavy metals from soil but also to improve soil quality.Here, we evaluated how the joint effect of Streptomyces pactum(strain Act12) and inorganic(Hoagland’s solution) and organic(humic acid and peat) nutrients affected the phytoextraction practice of cadmium(Cd) and zinc(Zn) by potherb mustard, and the microbial community composition within rhizosphere was also investigated.The results indicated that the nutrients exerted synergistically with Act12, all increasing the plant biomass and Cd/Zn uptakes.The inoculation of Act12 alone significantly increased dehydrogenase activity of rhizosphere soil(P<0.05), while urease and alkaline phosphatase activities varied in different dosage of Act12.Combined application of microbial strain with nutrients increased enzymatic activities with the elevated dosage of Act12.16S ribosomal RNA high-throughput sequencing analysis revealed that Act12 inoculation reduced the diversity of rhizosphere bacteria.The Act12 and nutrients did not change dominant phyla i.e.,Proteobacteria, Bacteroidetes, Gemmatimonadetes, Actinobacteria and Acidobacteria, but their relative abundance differed among the treatments with: Peat>Act12>Humic acid >Hoagland’s solution.Comparatively, Sphingomonas replaced Thiobacillus as dominant genus after Act12 application.The increase in the Sphingomonas and Flavisolibacter abundances under Act12 and nutrients treatments gave rise to growth-promoting effect on plant.Our results revealed the important role for rhizosphere microbiota in mediating soil biochemical traits and plant growth, and our approach charted a path toward the development of Act12 combined with soil nutrients to enhance soil quality and phytoextraction efficiency in Cd/Zn-contaminated soils.
基金This paper is a part of Hundred Talents Program granted by Chinese Academ y of Sciences.
文摘This paper will review the topic of phytoextraction,a major approach of phytoremediation,by clarifying the roles of hyperaccumulators,bio-mechanisms involved,issues regarding contaminant uptake,artificial chelation,genetic selection,and cultivation.The paper will also address the practical issues and the regulatory context of this emerging technology and briefly discuss avenues for future research.
基金This study was financially supported by Henan Land and Resources Department(2011-622-38).
文摘The plant samples of Bidens pilosa were collected from a coal gangue vacant site and its surrounding area,located in central China,to study the remediation effect of the plant species on heavy metal(HM)contamination in both natural and electrokinetic(EK)conditions.The analytical results showed that the effect of phytoextraction and bioconcentration on the heavy metals in the sample of the EK group is more significant than those in the other control group.Compared with the results of natural condition,under the EK condition the concentrations of cadmium(Cd),lead(Pb),copper(Cu)and zinc(Zn)in the stems and leaves of the Bidens pilosa increased to 0.40 mg/kg,4.23 mg/kg,7.27 mg/kg,830.24 mg/kg,respectively,with their increments of 292%,1731%,141%,2076%.For root samples,the Cd,Pb,Cu and Zn concentrations increased to 0.52 mg/kg,4.36 mg/kg,10.87 mg/kg,and 98.12 mg/kg and the increase rates were 1034%,140%,29%,and 181%,respectively.The phytoextraction efficiency of the Bidens pilosa was significantly higher than that of control group.The removal efficiency of Cd,Pb,Cu and Zn in soil increased to 26%,72%,27%,and 79%with the EK applied.In addition,the mechanism of HM migration,extraction and enrichment in Bidens pilosa under the EK condition was discussed.
基金Projects(31100082,60871007,61171061)supported by the National Natural Science Foundation of ChinaProject(2012SK4028)supported by the Science and Technology Agency of Hunan Province,China+1 种基金Project(2013M530358)supported by the Post-doctoral Program of ChinaProjects(12JJ4032,12JJ4082)supported by the Natural Science Foundation of Hunan Province,China
文摘Fungi Z4 and Z8, isolated from the heavy metal polluted soil, have strong resistance to Cd and Pb. The strains were identified on the base of their morphology and internal transcribed spacers(ITS) region. Pot experiments were conducted to study the effect of two strains(Z4 and Z8) on the growth and accumulation of Cd and Pb of Guizhou oilseed rape. The results show that strains Z4 and Z8 belong to Mucor circinelloides and Mucor racemosus, respectively. The heights of Guizhou oilseed rape inoculated with strain Z8 increase by 47.90% than the control. The highest fresh mass is found in the plant with Z4/Z8, which is enhanced by160.81%. Pot experiments show that Z4/Z8 inoculums can accelerate accumulation of heavy metals in the plant. The contents of Cd and Pb are increased by 117.60% and 63.48%, respectively. Meanwhile, the heavy metal concentrations in potting soil with the two strains are found to be lower than those of the control, and the concentrations of Cd and Pb are decreased by 60.57% and 27.12%,respectively.
文摘This study aims to assess the effective capacity of <i>Panicum</i><span> <i>maximum</i> </span>to accumulate cadmium (Cd), nickel (Ni) and lead (Pb). <i>P</i><span>. <i>maximum</i></span> observed in a greenhouse was subjected to 2 ppm of Cd, 50 ppm of Ni, 100 ppm of Pb contaminated soil and uncontaminated soil, </span></span><span><span><span style="font-family:"">for</span></span></span><span><span><span style="font-family:""> 120 days. Plant growth and biomass produced concentration of trace metals in soil and plant, bioaccumulation and transfer factors, location of potentially toxic elements in tissues and cells of plant ha</span></span></span><span><span><span style="font-family:"">ve</span></span></span><span><span><span style="font-family:""> been determined. Stem length and biomass produced by <i>P</i><span>. <i>maximum</i></span> were higher on the uncontaminated soil followed respectively by those of soil-contaminated by Pb, Cd and Ni. Bioaccumulation factors of trace metals were 8.93 (Pb), 8.47 (Ni) and 3.37 (Cd). Ni was more accumulated in shoot biomass (FT > 1), while Pb and Cd were concentrated in root biomass (FT </span></span></span><span><span><span style="font-family:""><</span></span></span><span><span><span style="font-family:""> 1). Pb is accumulated preferentially in endodermis (roots) and epidermis (leaves). As for Ni and Cd, they are concentrated in central cylinder of roots and in conductive bundles of leaves. At cellular level, Ni and Cd are mainly concentrated in intracellular compartments of leaves and roots, while Pb is strongly detected at cell walls.
文摘Neptunia amplexicaulis is an herbaceous legume endemic to the Richmond area in central Queensland,Australia and is one of the strongest known Selenium hyperaccumulators on earth,showing significant potential to be utilised in Se phytoextraction applications.Here a protocol was established for in vitro micropropagation of Se hyperaccumula-tor N.amplexicaulis using nodal segments from in vitro-germinated seedlings.Shoot multiplication was achieved on Murashige and Skoog(MS)basal media supplemented with various concentrations of 6-Benzylaminopurine(BA)(1.0,2.0,3.0 mg L^(−1))alone or in combination with low levels of Naphthaleneacetic acid(NAA)(0.1,0.2,0.3 mg L^(−1)),with 2.0 mg L^(−1) BA+0.2 mg L^(−1) NAA found to be most effective.Elongated shoots were rooted in vitro using NAA,with highest root induction rate of 30%observed at 0.2 mg L^(−1) NAA.About 95%of the in vitro rooted shoots survived acclimatization.Clonally propagated plantlets were dosed with selenate/selenite solution and assessed for Se tissue concentrations using Inductively Coupled Plasma Atomic Emission Spectroscopy(ICP-AES)and found to retain their ability to hyperaccumulate.The protocol developed for this study has potential to be optimised for generating clonal plants of N.amplexicaulis for use in research and phytoextraction industry applications.
文摘A greenhouse study was conducted on phytoextraction and accumulation of lead (Pb) and cadmium (Cd) from contaminated soil – water microcosms by the narrow-leaved cattail, Typha angustifolia. The plants were grown in sandy loam soil containing 1,666 and 38.5 mg/L of Pb(NO3)2 and Cd(NO3)2 respectively. The trends of lead and cadmium by T. angustifolia for all soil – water microcosms suggested interaction effects as decreased soil lead concentrations and increased water cadmium concentrations over time. T. angustifolia expressed trends as increased biomass in all contaminated shoots and roots examined. Cadmium uptake in shoot and root biomass slightly decreased when lead was initially added to the soil but cadmium uptake in root biomass increased after 30 days. Data suggested an interaction between lead and cadmium and possible that lead uptake was inhibited when cadmium was present.
文摘Phytoextraction has been introduced as a new technology to clean up soils contaminated with heavy metals as the use of conventional methods to clean up the soil is very expensive and destructive to the ecosystem. However, using plants to clean up contaminated soils takes a considerable period before the contaminants are removed from the soil by the plants. This has necessitated the use of amendments to enhance phytoextraction in order to shorten the period of contaminants removal by plants. In view of this, a pot experiment was conducted to study the effect of various aminopolycarboxylic acids (EDTA, EDDS, NTA dry and NTA liquid) and two commercial fertilizers which are Hortrilon? and Fetrilon? on their ability to solubilize Cd and Zn in contaminated soils. It was observed that the inducing effect of EDTA on the solubility of Cd and Zn persisted throughout the experimental period. Initially, EDDS enhanced the solubility Cd and Zn, however, its effect dissipated with time. The application of both NTA dry (powder) and NTA liquid had a significant effect on the solubility of Zn as a result of the formation of Zn-NTA soluble complexes. Hortrilon? and Fetrilon? solubilized significant concentrations of both Cd and Zn with Hortrilon? having the greatest inducing effect on the solubility of Cd and Zn.
文摘This study aims to investigate the capacity of <i>Chrysopogon</i> <i>nigritanus</i> to accumulate As from contaminated soils<i>.</i><b> </b>The experiment was conducted in a greenhouse. <i>C.</i> <i>nigritanus</i> was subjected to uncontaminated soil and As contaminated soil (50 mg/kg, 100 mg/kg and 150 mg/kg of As), for 180 days. Plant growth and biomass produced, concentration of As in soil and plant, bioaccumulation and transfer factors, as the location of As in tissues and cells of the plant have been determined. Plant growth decreased significantly with increasing of soil As concentration. <i>C.</i> <i>nigritanus</i> accumulated more As in roots biomass. The highest bioaccumulation factor values were found in contaminated soil at 50 mg As/kg (As 50), then contaminated soil at 100 mg As/kg (As 100) and contaminated soil at 150 mg As/kg (As 150). As was essentially fixed to the intracellular compartment of the roots, stems and leaves. In roots tissues, As was mainly retained in the rhizodermis and the pericycle. While in stems tissues, As was preferentially accumulated in the conductive bundles. In the leaves, the final destination of As was epidermis tissues.
基金the financial support from the project of the Ministry of Science and Higher Education of Russian Federation on the Young Scientist Laboratory within the framework of the Interregional Scientific and Educational Center of the South of Russia(No.FENW-2024-0001)the Strategic Academic Leadership Program of the Southern Federal University,Russia(Priority 2030)the Science and Engineering Research Board,Govt.of India for providing financial assistance(SERB/EEQ/2021/000735)。
文摘Escalating anthropogenic activities have caused heavy metal contamination in the environmental matrices.Due to their recalcitrant and toxic nature,their occurrence in high titers in the environment can threaten survival of biotic components.To take the edge off,remediation of metal-contaminated sites by phytoremediators that exhibit a potential to withstand heavy metal stress and quench harmful metals is considered an eco-sustainable approach.Despite the enormous potential,phytoremediation technique suffers a setback owing to high metal concentrations,occurrence of multiple pollutants,low plant biomass,and soil physicochemical status that affect plants at cellular and molecular levels,inducing morphological,physiological,and genetic alterations.Nevertheless,augmentation of soil with microorganisms can alleviate the challenge.A positive nexus between microbes,particularly plant growth-promoting microorganisms(PGPMs),and phytoremediators can prevent phytotoxicity and augment phytoremediation by employing strategies such as production of secondary metabolites,solubilization of phosphate,and synthesis of 1-aminocyclopropane-1-carboxylic acid(ACC)deaminase and phytohormones.Microbes can mediate tolerance in plants by fortifying their antioxidant machinery,which maintains redox homeostasis and alleviates metal-induced oxidative damage in the plants.Associated microbes can also activate stress-responsive genes in plants and abridge metal-induced toxic effects.An in-depth exploration of the mechanisms employed by plant-associated microbes to trigger tolerance in phytoremediators is crucial for improving their phytoremediation potential and real-world applications.The present article attempts to comprehensively review these mechanisms that eventually facilitate the development of improved/new technology for soil ecosystem restoration.
基金supported by the Yibin Science and Technology Plan(2022NY011).
文摘Soil metal pollution is a global issue due to its toxic nature affecting ecosystems and human health. This has become a concern since metals are non-biodegradable and toxic. Most of the reclamation methods currently used for soils rely on the use of physical and chemical means, which tend to be very expensive and result in secondary environmental damage. However, microbe-aided phytoremediation is gaining attention as it is an eco-friendly, affordable, and technically advanced method to restore the ecosystem. It is essential to understand the complex interaction between plants and microbes. The primary function of plant growth-promoting bacteria (PGPB) is to stimulate plant development, aid in metal elimination, and reduce their bioavailability in the soil. These microbes regulate phytohormones, stimulate processes such as phytoextraction and phyto-stabilization, and improve the uptake of essential nutrients, such as nitrogen and phosphorus. PGPBs secrete a range of enzymes and chemicals, fix nitrogen, solubilize minerals, increase the bioavailability of nutrients under diverse biological environments with high salinities, excessive metal-contaminated soil, and organic pollutants, increase the soil fertility and help in the reclamation of agriculture and regenerate the native flora. The integration of CRISPR-Cas9 gene-editing technology with microbial-aided phytoremediation and the use of genetically modified microbes with nanomaterials further enhance the efficacy of the approaches in polluted environments for sustainable restoration of the soil.
文摘Exogenous application of chelators towards enhancing heavy metals extraction efficiency of bioenergy crop has received considerable attention in recent time.However,little is known about optimal application rate,comparative evaluation of degradable versus non-degradable chelators and their impact on cadmium(Cd)speciation and uptake,physiological and biochemical activity of sweet sorghum grown under Cd stress.Four chelators namely,Nitrilotriacetic acid(NTA),tetrasodium N,N-diacetate(TDA),Ethylenediamine tetraacetic acid(EDTA),iminodisuccinic acid(IDA)and control(CK)were applied and compared at rates of 2,5,and 10 mmol kg^(-1) towards augmenting phytoextraction efficiency of sweet sorghum for Cd remediation in a screen house study.Results showed that sweet sorghum augmented with TDA significantly(P<0.05)increased biomass,enhanced Cd uptake and accumulation when compared to EDTA at application rate of 2-5 mmol kg1.TDA influenced Cd speciation via increasing acid-soluble,reducible,oxidizable,and residual fractions of Cd,thus increasing Cd bioavailability.NTA and TDA increased proline concentrations,antioxidant enzymes and net photosynthetic activity rate(Pn)comparably to EDTA in sweet sorghum,thus enhancing stress tolerance and stabilizing photosynthetic activities.Overall,exogenous application of degradable TDA at 2-5 mmol kg^(-1) could be recommended as replacement for non-degradable EDTA in a chelate assisted approach towards augmenting bioenergy crop for phytoremediation of Cd polluted soil.
基金the National Natural Science Foundation of China(41671315,41977107)National Postdoctoral Program for Innovative Talents(BX20200293)+3 种基金Zhejiang Provincial Natural Science Foundation of China(LZ18D010001)National Key Research and Development Project of China(2016YFD0800802)the Fundamental Research Funds for the Central Universities,China's Agriculture Research System(CARS-04)Fundamental Research Funds for the Central Universities(2020FZZX001-06).
文摘Chelating agent is known as the enhancer for metal phytoextraction;however,there is still a lack of efficient and environmentally sustainable chelators.Here,lemon residue extraction(LRE),prepared from 11 kinds of fruit wastes,was combined with N,N-bis(carboxymethyl)glutamic acid(GLDA),and tea saponin(T.S.)for the compounded plant-derived chelator(CPC),and their influences on Cd phytoextraction by the hyperaccumulator Sedum alfredii was evaluated.Among these fruits,the lemon residue extracted the most significant amount of Cd from the soil.The most effective CPC was at the volume ratio of three agents being 15:4:1(LRE:GLDA:T.S.).Compared with the deionized water,the solubility of three Cd minerals was increased by 85–256 times,and Cd speciation was substantially altered after CPC application.In the pot experiment,CPC addition caused evident increases in plant shoot biomass,Cd phytoextraction efficiency,and organic matter content compared with EDTA and nitrilotriacetic acid(NTA)application.CPC induced fewer changes in bacterial community composition compared with EDTA and had no pronounced influence on microbial biomass carbon and bacterialα-diversity,suggesting CPC had a subtle impact on the microbiological environments.Our study provides a theoretical base for the reutilization of fruit wastes and the development of environmental-friendly chelator that assists Cd phytoextraction.
基金Project supported by the National Natural Science Foundation of China(No.20477029,20337010)the National Basic Research Program(973)of China(No.2004CB18506).
文摘Soil contaminated with heavy metals cadmium （Cd） and lead （Pb） is hard to be remediated. Phytoremediation may be a feasible method to remove toxic metals from soil, but there are few suitable plants which can hyperaccumulate metals. In this study, Cd and Pb accumulation by four plants including sunflower （Helianthus annuus L.）, mustard （Brassicajuncea L.）, alfalfa （Medicago sativa L.）, ricinus （Ricinus communis L.） in hydroponic cultures was compared. Results showed that these plants could phytoextract heavy metals, the ability of accumulation differed with species, concentrations and categories of heavy metals. Values of BCF （bioconcentration factor） and TF （translocation factor） indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals. Changes on the biomass of plants, pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures. Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals, such as pH and Eh regulations, and so forth.
基金Supported by the Research Grant Council,Hong Kong SAR,China
文摘Metal contamination in the environment is a global concern due to its high toxicity to living organisms and its worldwide distribution. The principal goal of this review is to examine the current strategies and technologies for the remediation of metal- contaminated soils by metal-accumulating plants and assess the roles of arbnscular mycorrhizal （AM） fungi in remediation of soils under hyperaccumulator or non-accumulator plants. The use of plants to remove metals from the environment or reduce the toxicity, known as phytoremediation, is an environmentally sustainable and low cost remediation technology. The mechanisms of the use of hyperaccumulator plants for phytoremediation included solubilization of the metal in the soil matrix, the plant uptake of the metal, detoxification/chelation and sequestration, and volatilization. Recently, some ecologists have found that phytoremediation with the aids of mycorrhizae can enhance efficiency in the removal of toxic metals. AM fungi can facilitate the survival of their host plants growing on metal-contaminated land by enhancing their nutrient acquisition, protecting them from the metal toxicity, absorbing metals, and also enhancing phytostabilization and phytoextraction. Such information may be useful for developing phytoremediation program at metal-contaminated sites.
基金supported by the National Natural Science Foundation of China (Nos. 21376251 and 21406233)the National Basic Research Program (973) of China (No. 2013CB632600)
文摘A soil–plant biological system was developed from chromium（Cr） polluted soil treated by the compost-phytoremediation method. The transformation and migration of the Cr in this system is comprehensively studied in this research. The results illustrated that the co-composting treatment can reduce the Cr availability from 39%（F1 was about 31% of total, F2 was about 8% of total） to less than 2% by stabilizing the Cr. However, herbaceous plants can accumulate the concentrations of Cr from 113.8 to 265.2 mg/kg in the two crops,even though the concentration of soluble Cr in the substrate soil was below 0.1 mg/L.Cr can be assimilated and easily transferred in the tissues of plants because the lowmolecular-weight organic-acids（LMWOAs） derived from the plant root increase the bioavailability of Cr. The amount of extracted Cr dramatically increased when the organic acids were substituted in this order： citric acid 〉 malic acid 〉 tartaric acid 〉 oxalic acid 〉acetic acid. On average the maximum（147.4 mg/kg） and the minimum（78.75 mg/kg） Cr were extracted by 20 mmol/L citric acid and acetic acid, respectively. The desorption of Cr in different acid solutions can be predicted by the pseudo second-order kinetics. The exchangeable Cr, carbonate-bound Cr, and residual Cr decreased, while Fe–Mn oxide bound Cr and organic bound Cr increased in the soil solid phase. According to the experimental results, the organic acids will promote the desorption and chelation processes of Cr, leading to the remobilization of Cr in the soil.
基金supported by the Hi-Tech Re-search and Development Program (863) of China (No2007AA061001 and 2006AA06Z359)the National Nat-ural Science Foundation of China (No 40471117 and 30670393)the Planned Science and Technolo-gy Research Programs of Guangdong Province (No2006A36703004)
文摘The growth of high biomass crops facilitated by optimal of agronomic practices has been considered as an alternative to phytoremediation of soils contaminated by heavy metals. A field trial was carded out to evaluate the phytoextraction efficiency of heavy metals by three varieties of sweet sorghum （Sorghum biocolor L.）, a high biomass energy plant. Ethylene diamine tetraacetate （EDTA）, ammonium nitrate （NH4NO3） and ammonium sulphate （（NH4）2SO4） were tested for their abilities to enhance the removal of heavy metals Pb, Cd, Zn, and Cu by sweet sorghum from a contaminated agricultural soil. Sorghum plants always achieved the greatest removal of Pb by leaves and the greatest removal of Cd, Zn and Cu by stems. There was no significant difference among the Keller, Rio and Mray varieties of sweet sorghums in accumulating heavy metals. EDTA treatment was more efficient than ammonium nitrate and ammonium sulphate in promoting Pb accumulation in sweet sorghum from the contaminated agricultural soil. The application of ammonium nitrate and ammonium sulphate increased the accumulation of both Zn and Cd in roots of sorghum plants. Results from this study suggest that cropping of sorghum plants facilitated by agronomic practices may be a sustainable technique for partial decontamination of heavy metal contaminated soils.
基金supported by Zhejiang Science and Technology Bureau(No.2018C02029)the National Natural Science Foundation of China(Nos.41721001 and 31872956)+1 种基金Ministry of Science and Technology of China(No.2016YFD0800805)the Fundamental Research Funds for the Central Universities
文摘Phytoremediation is a valuable technology for mitigating soil contamination in agricultural lands,but phytoremediation without economic revenue is unfeasible for land owners and farmers.The use of crops with high biomass and bioenergy for phytoremediation is a unique strategy to derive supplementary benefits along with remediation activities.Sunflower(Helianthus annuus L.)is a high-biomass crop that can be used for the phytoremediation of polluted lands with additional advantages(biomass and oil).In this study,40 germplasms of sunflower were screened in field conditions for phytoremediation with the possibility for oil and meal production.The study was carried out to the physiological maturity stage.All studied germplasms mopped up substantial concentrations of Pb,with maximum amounts in shoot>root>seed respectively.The phytoextraction efficiency of the germplasm was assessed in terms of the Transfer factor(TF),Metal removal efficiency(MRE)and Metal extraction ratio(MER).Among all assessed criteria,GP.8585 was found to be most appropriate for restoring moderately Pb-contaminated soil accompanied with providing high biomass and high yield production.The Pb content in the oil of GP.8585 was below the Food safety standard of China,with 59.5% oleic acid and 32.1% linoleic acid.Moreover,amino acid analysis in meal illustrated significant differences among essential and nonessential amino acids.Glutamic acid was found in the highest percentage(22.4%),whereas cysteine in the lowest percentage(1.3%).Therefore,its efficient phytoextraction ability and good quality edible oil and meal production makes GP.8585 the most convenient sunflower germplasm for phytoremediation of moderately Pb-contaminated soil,with fringe benefits to farmers and landowners.
