Abstract: The authors found five sodium (Na+) and chloride (Cl-.) hyperaccumulating halophytes in the Temperate Desert of Xinjiang, China and studied two of them (Suaeda salsa (L.) Pall. and Kalidium folium (Pall.) Mo...Abstract: The authors found five sodium (Na+) and chloride (Cl-.) hyperaccumulating halophytes in the Temperate Desert of Xinjiang, China and studied two of them (Suaeda salsa (L.) Pall. and Kalidium folium (Pall.) Moq.). K. folium and S. salsa had a NaCl content of 32.1% and 29.8%, respectively, on a dry weight basis. X-ray microanalysis of the Na+ in the vacuole, apoplasts and cytoplasm of the two plants indicated a ratio of 7.3:5.6:1.0 in K. folium and 7.3:6.6:1.0 in S. salsa. These data show that K. folium and S. salsa both have a high Na+ and Cl- accumulating capacity, which is related to high activity of tonoplast H+-ATPase and H+-PPase.展开更多
Sedum alfredii Hance has been identified as a new Zn-hyperaccumulator native to China. In this study, responses and metal accumulation of S alfredii were examined under Zn/Cd complex polluted conditions. The results s...Sedum alfredii Hance has been identified as a new Zn-hyperaccumulator native to China. In this study, responses and metal accumulation of S alfredii were examined under Zn/Cd complex polluted conditions. The results showed that optimal growth of S alfredii in terms of the maximum dry matter yield was observed at Zn/Cd complex level of 500/100 mumol/L. Plant cadmium (Cd) or zinc (Zn) concentrations increased with increasing Cd or Zn supply. During the 20 d treatment, the highest Cd concentration in the leaves reached 12.1 g/kg at Zn/Cd level of 50/400 mumol/L and that of Zn in the stems was 23.2 g/kg at Zn/Cd level of 1000/50 mumol/L. The distribution of Cd in different plant parts decreased in the order: leaf > stem greater than or equal to root, whereas that of Zn was: stem > leaf greater than or equal to root. The accumulation of Cd and Zn in the shoots and roots of S. alfredii increased with the increasing of Zn/Cd supply levels, peaked at Zn/Cd levels of 250/400 and 500/100 mumol/L, respectively. The highest Cd and Zn uptake by the shoots was approximately 5 and 11 mg/plant, and was over 20 and 10 times higher than those in the roots, respectively. Zn supply at levels less than or equal to 500 mumol/L increased plant Cd concentrations, whereas high Zn supply decreased root Cd but did not affect leaf Cd concentrations in S alfredii Low Cd supply increased Zn concentration in the leaves, but Cd supply higher than 50 mumol/L considerably reduced root Zn concentrations, especially at low Zn level. These results indicate that S. alfredii can tolerate high Zn/Cd complex levels and has an extraordinary ability to hyperaccumulate not only Zn but also Cd. It could provide a new valuable plant material for understanding the mechanisms responsible for co-hyperaccumulation of Zn and Cd as well as for phytoremediation of the Cd/Zn complex polluted soils.展开更多
Four species of Sedum L. were grown in nutrient solution for the comparison of their Zn uptake and accumulation. S. alfredii Hance showed much greater tolerance to Zn than the other three species. Shoot and root yield...Four species of Sedum L. were grown in nutrient solution for the comparison of their Zn uptake and accumulation. S. alfredii Hance showed much greater tolerance to Zn than the other three species. Shoot and root yields of S. sarmentosum Bunge, S. bulbiferum Makino, and S. emarginatum Migo decreased with increasing Zn concentration in the solution, while shoot and root yields of S. alfredii increased when Zn concentration was ≤80 mg·L -1. At 80 mg·L -1 Zn, Zn concentration in shoots of S. alfredii reached 19.09 mg·g -1. S. alfredii was also more efficient in Zn translocation from roots to shoots, while Zn concentration in shoots was much higher than in roots. However, this was not the case for the other three species. The results showed that S. alfredii is a Zn hyperaccumulator and could be useful for the phytoremediation of Zn-contaminated soils.展开更多
Phytoremediation is an efficient and economic ecological technology. It includes phytostabilization, phytovolatilization, and plant absorption. In the research, status quo and progress of Phytostabilization and plant ...Phytoremediation is an efficient and economic ecological technology. It includes phytostabilization, phytovolatilization, and plant absorption. In the research, status quo and progress of Phytostabilization and plant absorption in soils polluted with heavy metals in metal mines were summarized, including the characteristics and status quo of phytoremediation and selection method of hyperaccumulator. In addition, further research was proposed as well.展开更多
A new way is described to recover nickel from common rock-types, by the use of nickel hyperaccumulator plants. The idea of phytomining nickel was suggested earlier, but never implemented. This situation may soon chang...A new way is described to recover nickel from common rock-types, by the use of nickel hyperaccumulator plants. The idea of phytomining nickel was suggested earlier, but never implemented. This situation may soon change, because the mining sector suffers from a poor image on account of the impact of mining on the environment, and would like to reduce the pollution and high energy consumption associated with metal extraction. Once phytomining is established as a viable way of nickel production, it is likely that governments will impose nickel mines to realize part of their nickel production by this method. This will lead to a considerable decrease of CO2 emissions. Phytomining from rocks rich in olivine or serpentine is CO2-negative. When metal extraction goes hand in hand with CO2 sequestration, it will improve the image of the mining sector. Other advantages include that unproductive soils can serve to grow nickel hyperaccumulator plants and recover nickel. The extensive mining technology can provide employment to many poor farmers/miners. Countries that want to be self-sufficient in strategic materials, and avoid spending foreign currency on importing them can switch to phytomining. This paper treats different aspects of future nickel farming.展开更多
Pteridophyta are vascular plants(plants with xylem and phloem) that reproduce and disperse via spores. In evolution,pteridophyta lie between bryophyta and spermatophyta. Pteridophyta have unique ecological characteris...Pteridophyta are vascular plants(plants with xylem and phloem) that reproduce and disperse via spores. In evolution,pteridophyta lie between bryophyta and spermatophyta. Pteridophyta have unique ecological characteristics of high environmental adaptation and barren resistance. Some varieties of pteridophyta have ability of excessive absorption and accumulation of heavy metals such as arsenic(As) and antimony(Sb). Besides,pteridophyta have excellent performance in absorbing such heavy metals as cadmium(Cd),lead(Pb),copper(Cu),and nickel(Ni),and rare earth elements. In this paper,a review was made for application,mechanism,and advantages of pteridophyta in remediation of heavy metal contaminated environments,and prospect and possible research fields of pteridophyta in phytoremediation were discussed.展开更多
At the present manuscript,a brief report is given concerning heavy metals soil bioremediation methods and particularly phytoextraction by means of hyper-accumulator plants.The picking of the plants i.e.Thlaspi caerule...At the present manuscript,a brief report is given concerning heavy metals soil bioremediation methods and particularly phytoextraction by means of hyper-accumulator plants.The picking of the plants i.e.Thlaspi caerulescens should meet certain requirements according to already conducted experiments.Cultivations’data of the aforementioned Cd and Zn phytoaccumulator species are demonstrated.The last part incorporates a case study of a heavy metal-contaminated area nearby an abandoned lead-zinc mine located somewhere in NE(Northeast)Greece and a fundamental operational&cost analysis of the whole remediation project.展开更多
Cadmium(Cd) contamination has posed an increasing challenge to environmental quality and food security. In recent years,phytoremediation has been particularly scrutinized because it is cost-effective and environmental...Cadmium(Cd) contamination has posed an increasing challenge to environmental quality and food security. In recent years,phytoremediation has been particularly scrutinized because it is cost-effective and environmentally friendly, especially the use of metal-hyperaccumulating plants to extract or mine heavy metals from polluted soils. Under Cd stress, responses of hyperaccumulator and non-hyperaccumulator plants differ in morphological responses and physiological processes such as photosynthesis and respiration,uptake, transport, and assimilation of minerals and nitrogen, and water uptake and transport, which contribute to their ability to accumulate and detoxify Cd. This review aims to provide a brief overview of the recent progresses in the differential responses of hyperaccumulator and non-accumulator plants to Cd toxicity in terms of growth and physiological processes. Such information might be useful in developing phytoremediation technology for contaminated soils.展开更多
Soil contamination by heavy metals is a serious environmental problem worldwide, and reduction of heavy metal accumulation in vegetables grown on contaminated land is a matter of urgency. A pot experiment was conducte...Soil contamination by heavy metals is a serious environmental problem worldwide, and reduction of heavy metal accumulation in vegetables grown on contaminated land is a matter of urgency. A pot experiment was conducted to study the effects of intercropping with the Cd hyperaccumulators Solanum nigrum and Solanum photeinocarpum from two ecoclimatic regions, Ya＇an and Chengdu, Sichuan Province, China, on the growth and cadmium （Cd） uptake of eggplant （Solanum melongena L.）. The biomass, photosynthetic pigment contents, and activities of antioxidant enzymes of eggplant were enhanced by intercropping. The biomass of eggplant was the highest after intercropping with S. photeinocarpum from Ya＇an, but did not differ significantly from that after intercropping with S. nigrum from Chengdu. The shoot Cd content of eggplant was significantly reduced by intercropping with the hyperaccumulators, which ranked as follows： S. nigrum from Chengdu 〉 S. nigrum from Ya＇an 〉 S. photeinocarpum from Chengdu 〉 S. photeinocarpum from Ya＇an, with the decreases being 19.60%, 14.36%, 9.66%, and 6.42%, respectively, as compared with the control. The lowest shoot Cd content and translocation factor of eggplant were attained after intercropping with S. nigvum from Chengdu. Therefore, it was feasible to intercrop eggplant with S. nigrum and S. photeinocarpurn on Cd-contaminated soil.展开更多
Hyperaccumulators concentrate trace metals and heavy metals in their shoots when grown in metal-contaminated soils and these trace metal-loaded plants may be removed by harvesting the fields. Studies exploring the ben...Hyperaccumulators concentrate trace metals and heavy metals in their shoots when grown in metal-contaminated soils and these trace metal-loaded plants may be removed by harvesting the fields. Studies exploring the beneficial role of these hyperaccumulators to clean up the environment have led to the development of phytoextraction. The success of phytoextraction depends upon the high biomass of plant species and bioavailability of metals for plant uptake. The phytoavailability of metals is influenced by soil- associated factors, such as pH, redox potential, cation exchange capacity, soil type, and soil texture, and by plant-associated factors, such as root exudates and root rhizosphere processes （microorganisms）. Efficiency of phytoextraction can be improved by advanced agronomic practices including soil and crop management by application of genetic engineering to enhance the metal tolerance, shoot translocation, accumulation, and sequestration and by application of chelate treatments to enhance metal bioavailability. Application of microorganisms including bacteria and mycorrhiza may facilitate the phytoextraction application at commercially large scale.展开更多
To screen out a series of ideal plants that can effectively remedy contaminated soils by heavy metals is the main groundwork of phytoremediation engineering and the first step of its commercial application on a large ...To screen out a series of ideal plants that can effectively remedy contaminated soils by heavy metals is the main groundwork of phytoremediation engineering and the first step of its commercial application on a large scale. In this study, accumulation and endurance of 45 weed species in 16 families from an agricultural site were in situ examined by using the pot-culture field experiment, and the remediation potential of some weed species with high accumulation of heavy metals was assayed. The results showed that Solanum nigrum and Conyza canadensis can not only accumulate high concentration of Cd, but also strongly endure to single Cd and Cd-Pb-Cu-Zn combined pollution. Thus 2 weed species can be regarded as good hyperaccumulators for the remediation of Cd-contaminated soils. Although there were high Cd-accumulation in Artemigia selengensis, Znula britannica and Cephalanoplos setosum, their biomass was adversely affected due to action of heavy metals in the soils. If the problem of low endurance to heavy metals can be solved by a reinforcer, 3 weed species can be perhaps applied commercially.展开更多
Agrogyron elongatum were grown in nutrient solution containing moderate to high amounts of separate heavy metal of Cd, Cu, Ni and Ph in a greenhouse for a 9 - day. Cd, Cu, Ni and Ph generally led to decrease in the el...Agrogyron elongatum were grown in nutrient solution containing moderate to high amounts of separate heavy metal of Cd, Cu, Ni and Ph in a greenhouse for a 9 - day. Cd, Cu, Ni and Ph generally led to decrease in the elongation of roots although the length of seedlings exposed to Cd and Ph at 0.05 and 0.5 mg/L showed to be slightly greater than that of controls. Of the four metals in the experiment, Ph was absorbed and accumulated to the highest level, with the concentrations of 92754 mg/kg dry weight (DW) in roots and 11683 mg/kg DW in shoots. Cd was moderately accumulated in Agrogyron elongatum, but the maximum bioaccumulation coefficients (BCs) for roots and shoots were observed. The patterns for Cu and Ni uptake and distribution in plants differed from those of Ph and Cd, as it was showed that the shoot accumulation of Cu and Ni was significantly higher than in roots. A. elongation had the highest Ni concentration in shoots (30261 mg/kg DW) at the external concentration of 250 mg/L. Cu ranked second, with a shoot concentration of 12230 mg/kg DW when 50 mg/L Cu in solution was applied. For the four trace elements tested, the highest concentrations in shoots decreased by the order of Ni > Cu > Ph > Cd (mg/kg DW), and those in roots were Ph > Cd > Ni > Cu (mg/kg DW). Malic, oxalic and citric acids exuded by roots exposed to 1 and 50 mg/L of the metals were detected. Release of organic acids from plants significantly differed among the metal treatments. Cu was most effectively in inducing root exudation of the three types of organic acids. Cd, and Ni were also the inducers of secretion of malic and oxalic acids. With reference of Pb, a small amounts of malic and oxalic acids were detected in the root exudates, but few quantities, of citric acid were. found. However, no correlation between alternations in root exudation of organic acids and metal accumulation could be established.展开更多
Considering that even contaminated soils are a potential resource for agricultural production, it is essential to develop a set of cropping systems to allow a safe and sustainable agriculture on contaminated lands whi...Considering that even contaminated soils are a potential resource for agricultural production, it is essential to develop a set of cropping systems to allow a safe and sustainable agriculture on contaminated lands while avoiding any transfer of toxic trace elements to the food chain. In this review, three main strategies, i.e., phytoexclusion, phytostabilization, and phytoextraction, are proposed to establish cropping systems for production of edible and non-edible plants, and for extraction of elements for industrial use. For safe production of food crops, the selection of low-accumulating plants/cultivars and the application of soil amendments are of vital importance. Phytostabilization using non-food energy and fiber plants can provide additional renewable energy sources and economic benefit with minimum cost of agricultural measures. Phytoextracting trace elements （e.g., As, Cd, Ni, and Zn） using hyperaccumulator species is more suitable for slightly and moderately polluted sites, and phytomining of Ni from serpentine soils has shown a great potential to extract Ni-containing bio-ores of economic interests. We conclude that appropriate combinations of soil types, plant species/cultivars, and agronomic practices can restrict trace metal transfer to the food chain and/or extract energy and metals of industrial use and allow safe agricultural activities.展开更多
Zn accumulation and subcellular distribution in leaves of the hyperaccumulating ecotype （HE） and non-hyperaccumulating ecotype （NHE） of Sedum alfredii Hance were studied using radiotracer and gradient centrifugati...Zn accumulation and subcellular distribution in leaves of the hyperaccumulating ecotype （HE） and non-hyperaccumulating ecotype （NHE） of Sedum alfredii Hance were studied using radiotracer and gradient centrifugation techniques. Leaf Zn accumulation in the HE of S. alfredii was 18.5-26.7 times greater than that in the NHE when the plants were grown at 1-500μmol Zn L-1. Leaf section uptake of 65Zn was highly dependent on external Zn levels. Greater 65Zn uptake in HE was noted only at external Zn levels 〉 100μmol L-1. Zinc subcellular distribution in the leaves of the two ecotypes of S. alfredii was： cell wall 〉 soluble fraction 〉 cell organelle. However, more Zn was distributed to the leaf cell wall and soluble fractions for HE than for NHE. In the leaf of HE, 91%-94% of the Zn was found in the cell walls and the soluble fraction and only 6%-9% Zn was distributed in the cell organelle fraction. For NHE, about 20%-26% Zn was recovered in the cell organelle fraction. In stems, Zn distribution to the ceil wail fraction was approximately two fold greater in the HE than that in the NHE. For the hyperaccumulating ecotype of S. alfredii, the cell wall and the vacuole played a very important role in Zn tolerance and hyperaccumulation.展开更多
The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils.Organic acid has been suggested to be involved in toxic metall...The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils.Organic acid has been suggested to be involved in toxic metallic element tolerance,translocation,and accumulation in plants.The impact of exogenous organic acids on cadmium(Cd) uptake and translocation in the zinc(Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study.By the addition of organic acids,short-term(2 h) root uptake of 109 Cd increased significantly,and higher 109 Cd contents in roots and shoots were noted 24 h after uptake,when compared to controls.About 85% of the 109 Cd taken up was distributed to the shoots in plants with citric acid(CA) treatments,as compared with 75% within controls.No such effect was observed for tartaric acid(TA).Reduced growth under Cd stress was significantly alleviated by low CA.Long-term application of the two organic acids both resulted in elevated Cd in plants,but the effects varied with exposure time and levels.The results imply that CA may be involved in the processes of Cd uptake,translocation and tolerance in S.alfredii,whereas the impact of TA is mainly on the root uptake of Cd.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
The pollution of soils by heavy metals has dramatically increased in recent decades. Phytoextraction is a technology that extracts elements from polluted soils using hyperaccumulator plants. The selection of appropria...The pollution of soils by heavy metals has dramatically increased in recent decades. Phytoextraction is a technology that extracts elements from polluted soils using hyperaccumulator plants. The selection of appropriate plant materials is an important factor for successful phytoextraction in field. A field study was conducted to compare the efficiency of six high-biomass forage species in their phytoextraction of heavy metals(Cd, Pb, and Zn) from contaminated soil under two harvesting strategies(double harvesting or single harvesting). Among the tested plants, amaranth accumulated the greatest amounts of Cd and Zn, whereas Rumex K^(-1) had the highest amount of Pb in the shoot under both double and single harvesting. Furthermore, double harvesting significantly increased the shoot biomass of amaranth, sweet sorghum and sudangrass and resulted in higher heavy metal contents in the shoot. Under double harvesting, the total amounts of extracted Cd, Pb and Zn(i.e., in the first plus second crops) for amaranth were 945, 2 650 and 12 400 g ha^(-1), respectively, the highest recorded among the six plant species. The present results indicate that amaranth has great potential for the phytoextraction of Cd from contaminated soils. In addition, the double harvesting method is likely to increase phytoextraction efficiency in practice.展开更多
Commelina communis L. growing over some new copper mining wastelands at Bijiashan, Tongling City of Anhui Province, China, was found to be a copper hyperaccumulator. Its copper concentrations were 2707-6159 (4439±...Commelina communis L. growing over some new copper mining wastelands at Bijiashan, Tongling City of Anhui Province, China, was found to be a copper hyperaccumulator. Its copper concentrations were 2707-6159 (4439±2434) mg kg-1, 369-831 (731±142) mg kg-1, and 429-587 (547±57) mg kg-1, respectively, in the roots, stems, and leaves. The soils supporting the growth of the species had a copper concentration ranging from 4620 to 5020 mg kg-1 and averaging 4835±262 mg kg-1, suggesting that the species could not only grow on heavily copper-contaminated soils but also accumulate extraordinarily high concentration of copper. Thus, it shows great potential in the phytoremediation of copper-contaminated soils,the restoration of mined land, geochemical prospecting, and the study of environmental pollution changes.展开更多
Heavy metals are widely distributed contaminants in natural environments and their potential threats to human health have attracted worldwide concerns due to the food chain. Therefore, great efforts have been made to ...Heavy metals are widely distributed contaminants in natural environments and their potential threats to human health have attracted worldwide concerns due to the food chain. Therefore, great efforts have been made to reduce them to a safe level in soil. Compared with the traditional methods, the method using plants to remove them has been accepted as a feasible and efficient way. Herein, the geochemical behavior of heavy metals and the restoration methods with phytoremediation were reviewed. In addition, issues on heavy metal speciation as well as its influencing factors, phytoremediation mechanism, phytoremediation effect and vegetation selection principle used for phytoremediation were discussed.展开更多
基金国家重点基础研究发展计划(973计划)，the Foundation of Excellent Young/Scientists of Shandong Province
文摘Abstract: The authors found five sodium (Na+) and chloride (Cl-.) hyperaccumulating halophytes in the Temperate Desert of Xinjiang, China and studied two of them (Suaeda salsa (L.) Pall. and Kalidium folium (Pall.) Moq.). K. folium and S. salsa had a NaCl content of 32.1% and 29.8%, respectively, on a dry weight basis. X-ray microanalysis of the Na+ in the vacuole, apoplasts and cytoplasm of the two plants indicated a ratio of 7.3:5.6:1.0 in K. folium and 7.3:6.6:1.0 in S. salsa. These data show that K. folium and S. salsa both have a high Na+ and Cl- accumulating capacity, which is related to high activity of tonoplast H+-ATPase and H+-PPase.
文摘Sedum alfredii Hance has been identified as a new Zn-hyperaccumulator native to China. In this study, responses and metal accumulation of S alfredii were examined under Zn/Cd complex polluted conditions. The results showed that optimal growth of S alfredii in terms of the maximum dry matter yield was observed at Zn/Cd complex level of 500/100 mumol/L. Plant cadmium (Cd) or zinc (Zn) concentrations increased with increasing Cd or Zn supply. During the 20 d treatment, the highest Cd concentration in the leaves reached 12.1 g/kg at Zn/Cd level of 50/400 mumol/L and that of Zn in the stems was 23.2 g/kg at Zn/Cd level of 1000/50 mumol/L. The distribution of Cd in different plant parts decreased in the order: leaf > stem greater than or equal to root, whereas that of Zn was: stem > leaf greater than or equal to root. The accumulation of Cd and Zn in the shoots and roots of S. alfredii increased with the increasing of Zn/Cd supply levels, peaked at Zn/Cd levels of 250/400 and 500/100 mumol/L, respectively. The highest Cd and Zn uptake by the shoots was approximately 5 and 11 mg/plant, and was over 20 and 10 times higher than those in the roots, respectively. Zn supply at levels less than or equal to 500 mumol/L increased plant Cd concentrations, whereas high Zn supply decreased root Cd but did not affect leaf Cd concentrations in S alfredii Low Cd supply increased Zn concentration in the leaves, but Cd supply higher than 50 mumol/L considerably reduced root Zn concentrations, especially at low Zn level. These results indicate that S. alfredii can tolerate high Zn/Cd complex levels and has an extraordinary ability to hyperaccumulate not only Zn but also Cd. It could provide a new valuable plant material for understanding the mechanisms responsible for co-hyperaccumulation of Zn and Cd as well as for phytoremediation of the Cd/Zn complex polluted soils.
文摘Four species of Sedum L. were grown in nutrient solution for the comparison of their Zn uptake and accumulation. S. alfredii Hance showed much greater tolerance to Zn than the other three species. Shoot and root yields of S. sarmentosum Bunge, S. bulbiferum Makino, and S. emarginatum Migo decreased with increasing Zn concentration in the solution, while shoot and root yields of S. alfredii increased when Zn concentration was ≤80 mg·L -1. At 80 mg·L -1 Zn, Zn concentration in shoots of S. alfredii reached 19.09 mg·g -1. S. alfredii was also more efficient in Zn translocation from roots to shoots, while Zn concentration in shoots was much higher than in roots. However, this was not the case for the other three species. The results showed that S. alfredii is a Zn hyperaccumulator and could be useful for the phytoremediation of Zn-contaminated soils.
文摘Phytoremediation is an efficient and economic ecological technology. It includes phytostabilization, phytovolatilization, and plant absorption. In the research, status quo and progress of Phytostabilization and plant absorption in soils polluted with heavy metals in metal mines were summarized, including the characteristics and status quo of phytoremediation and selection method of hyperaccumulator. In addition, further research was proposed as well.
文摘A new way is described to recover nickel from common rock-types, by the use of nickel hyperaccumulator plants. The idea of phytomining nickel was suggested earlier, but never implemented. This situation may soon change, because the mining sector suffers from a poor image on account of the impact of mining on the environment, and would like to reduce the pollution and high energy consumption associated with metal extraction. Once phytomining is established as a viable way of nickel production, it is likely that governments will impose nickel mines to realize part of their nickel production by this method. This will lead to a considerable decrease of CO2 emissions. Phytomining from rocks rich in olivine or serpentine is CO2-negative. When metal extraction goes hand in hand with CO2 sequestration, it will improve the image of the mining sector. Other advantages include that unproductive soils can serve to grow nickel hyperaccumulator plants and recover nickel. The extensive mining technology can provide employment to many poor farmers/miners. Countries that want to be self-sufficient in strategic materials, and avoid spending foreign currency on importing them can switch to phytomining. This paper treats different aspects of future nickel farming.
基金Supported by Scientific Research Foundation of Yunnan Provincial Department of Education(2015Y296)Construction Project of Key Superior and Characteristic Disciplines in Colleges and Universities of Yunnan Province
文摘Pteridophyta are vascular plants(plants with xylem and phloem) that reproduce and disperse via spores. In evolution,pteridophyta lie between bryophyta and spermatophyta. Pteridophyta have unique ecological characteristics of high environmental adaptation and barren resistance. Some varieties of pteridophyta have ability of excessive absorption and accumulation of heavy metals such as arsenic(As) and antimony(Sb). Besides,pteridophyta have excellent performance in absorbing such heavy metals as cadmium(Cd),lead(Pb),copper(Cu),and nickel(Ni),and rare earth elements. In this paper,a review was made for application,mechanism,and advantages of pteridophyta in remediation of heavy metal contaminated environments,and prospect and possible research fields of pteridophyta in phytoremediation were discussed.
文摘At the present manuscript,a brief report is given concerning heavy metals soil bioremediation methods and particularly phytoextraction by means of hyper-accumulator plants.The picking of the plants i.e.Thlaspi caerulescens should meet certain requirements according to already conducted experiments.Cultivations’data of the aforementioned Cd and Zn phytoaccumulator species are demonstrated.The last part incorporates a case study of a heavy metal-contaminated area nearby an abandoned lead-zinc mine located somewhere in NE(Northeast)Greece and a fundamental operational&cost analysis of the whole remediation project.
基金supported by the National Natural Science Foundation of China (No. 41501521)a scholarship from the University of Florida, USA
文摘Cadmium(Cd) contamination has posed an increasing challenge to environmental quality and food security. In recent years,phytoremediation has been particularly scrutinized because it is cost-effective and environmentally friendly, especially the use of metal-hyperaccumulating plants to extract or mine heavy metals from polluted soils. Under Cd stress, responses of hyperaccumulator and non-hyperaccumulator plants differ in morphological responses and physiological processes such as photosynthesis and respiration,uptake, transport, and assimilation of minerals and nitrogen, and water uptake and transport, which contribute to their ability to accumulate and detoxify Cd. This review aims to provide a brief overview of the recent progresses in the differential responses of hyperaccumulator and non-accumulator plants to Cd toxicity in terms of growth and physiological processes. Such information might be useful in developing phytoremediation technology for contaminated soils.
基金supported by the Scientific Research Fund of Sichuan Provincial Education Department, China (No. 15ZA0011)the Scientific Research Fund of Sichuan Tobacco Monopoly Administration, China (No. SCYC201504)the Program for Creative Group Construction in "211 Project" of Sichuan Agricultural University, China
文摘Soil contamination by heavy metals is a serious environmental problem worldwide, and reduction of heavy metal accumulation in vegetables grown on contaminated land is a matter of urgency. A pot experiment was conducted to study the effects of intercropping with the Cd hyperaccumulators Solanum nigrum and Solanum photeinocarpum from two ecoclimatic regions, Ya＇an and Chengdu, Sichuan Province, China, on the growth and cadmium （Cd） uptake of eggplant （Solanum melongena L.）. The biomass, photosynthetic pigment contents, and activities of antioxidant enzymes of eggplant were enhanced by intercropping. The biomass of eggplant was the highest after intercropping with S. photeinocarpum from Ya＇an, but did not differ significantly from that after intercropping with S. nigrum from Chengdu. The shoot Cd content of eggplant was significantly reduced by intercropping with the hyperaccumulators, which ranked as follows： S. nigrum from Chengdu 〉 S. nigrum from Ya＇an 〉 S. photeinocarpum from Chengdu 〉 S. photeinocarpum from Ya＇an, with the decreases being 19.60%, 14.36%, 9.66%, and 6.42%, respectively, as compared with the control. The lowest shoot Cd content and translocation factor of eggplant were attained after intercropping with S. nigvum from Chengdu. Therefore, it was feasible to intercrop eggplant with S. nigrum and S. photeinocarpurn on Cd-contaminated soil.
文摘Hyperaccumulators concentrate trace metals and heavy metals in their shoots when grown in metal-contaminated soils and these trace metal-loaded plants may be removed by harvesting the fields. Studies exploring the beneficial role of these hyperaccumulators to clean up the environment have led to the development of phytoextraction. The success of phytoextraction depends upon the high biomass of plant species and bioavailability of metals for plant uptake. The phytoavailability of metals is influenced by soil- associated factors, such as pH, redox potential, cation exchange capacity, soil type, and soil texture, and by plant-associated factors, such as root exudates and root rhizosphere processes （microorganisms）. Efficiency of phytoextraction can be improved by advanced agronomic practices including soil and crop management by application of genetic engineering to enhance the metal tolerance, shoot translocation, accumulation, and sequestration and by application of chelate treatments to enhance metal bioavailability. Application of microorganisms including bacteria and mycorrhiza may facilitate the phytoextraction application at commercially large scale.
文摘To screen out a series of ideal plants that can effectively remedy contaminated soils by heavy metals is the main groundwork of phytoremediation engineering and the first step of its commercial application on a large scale. In this study, accumulation and endurance of 45 weed species in 16 families from an agricultural site were in situ examined by using the pot-culture field experiment, and the remediation potential of some weed species with high accumulation of heavy metals was assayed. The results showed that Solanum nigrum and Conyza canadensis can not only accumulate high concentration of Cd, but also strongly endure to single Cd and Cd-Pb-Cu-Zn combined pollution. Thus 2 weed species can be regarded as good hyperaccumulators for the remediation of Cd-contaminated soils. Although there were high Cd-accumulation in Artemigia selengensis, Znula britannica and Cephalanoplos setosum, their biomass was adversely affected due to action of heavy metals in the soils. If the problem of low endurance to heavy metals can be solved by a reinforcer, 3 weed species can be perhaps applied commercially.
文摘Agrogyron elongatum were grown in nutrient solution containing moderate to high amounts of separate heavy metal of Cd, Cu, Ni and Ph in a greenhouse for a 9 - day. Cd, Cu, Ni and Ph generally led to decrease in the elongation of roots although the length of seedlings exposed to Cd and Ph at 0.05 and 0.5 mg/L showed to be slightly greater than that of controls. Of the four metals in the experiment, Ph was absorbed and accumulated to the highest level, with the concentrations of 92754 mg/kg dry weight (DW) in roots and 11683 mg/kg DW in shoots. Cd was moderately accumulated in Agrogyron elongatum, but the maximum bioaccumulation coefficients (BCs) for roots and shoots were observed. The patterns for Cu and Ni uptake and distribution in plants differed from those of Ph and Cd, as it was showed that the shoot accumulation of Cu and Ni was significantly higher than in roots. A. elongation had the highest Ni concentration in shoots (30261 mg/kg DW) at the external concentration of 250 mg/L. Cu ranked second, with a shoot concentration of 12230 mg/kg DW when 50 mg/L Cu in solution was applied. For the four trace elements tested, the highest concentrations in shoots decreased by the order of Ni > Cu > Ph > Cd (mg/kg DW), and those in roots were Ph > Cd > Ni > Cu (mg/kg DW). Malic, oxalic and citric acids exuded by roots exposed to 1 and 50 mg/L of the metals were detected. Release of organic acids from plants significantly differed among the metal treatments. Cu was most effectively in inducing root exudation of the three types of organic acids. Cd, and Ni were also the inducers of secretion of malic and oxalic acids. With reference of Pb, a small amounts of malic and oxalic acids were detected in the root exudates, but few quantities, of citric acid were. found. However, no correlation between alternations in root exudation of organic acids and metal accumulation could be established.
基金Supported by the Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, China and the Chinese Scholarship Council
文摘Considering that even contaminated soils are a potential resource for agricultural production, it is essential to develop a set of cropping systems to allow a safe and sustainable agriculture on contaminated lands while avoiding any transfer of toxic trace elements to the food chain. In this review, three main strategies, i.e., phytoexclusion, phytostabilization, and phytoextraction, are proposed to establish cropping systems for production of edible and non-edible plants, and for extraction of elements for industrial use. For safe production of food crops, the selection of low-accumulating plants/cultivars and the application of soil amendments are of vital importance. Phytostabilization using non-food energy and fiber plants can provide additional renewable energy sources and economic benefit with minimum cost of agricultural measures. Phytoextracting trace elements （e.g., As, Cd, Ni, and Zn） using hyperaccumulator species is more suitable for slightly and moderately polluted sites, and phytomining of Ni from serpentine soils has shown a great potential to extract Ni-containing bio-ores of economic interests. We conclude that appropriate combinations of soil types, plant species/cultivars, and agronomic practices can restrict trace metal transfer to the food chain and/or extract energy and metals of industrial use and allow safe agricultural activities.
基金Project supported by the National Natural Science Foundation of China (No. 20277035)the National Key Basic Research Program (973 Program) of China (No. 2002CB410804).
文摘Zn accumulation and subcellular distribution in leaves of the hyperaccumulating ecotype （HE） and non-hyperaccumulating ecotype （NHE） of Sedum alfredii Hance were studied using radiotracer and gradient centrifugation techniques. Leaf Zn accumulation in the HE of S. alfredii was 18.5-26.7 times greater than that in the NHE when the plants were grown at 1-500μmol Zn L-1. Leaf section uptake of 65Zn was highly dependent on external Zn levels. Greater 65Zn uptake in HE was noted only at external Zn levels 〉 100μmol L-1. Zinc subcellular distribution in the leaves of the two ecotypes of S. alfredii was： cell wall 〉 soluble fraction 〉 cell organelle. However, more Zn was distributed to the leaf cell wall and soluble fractions for HE than for NHE. In the leaf of HE, 91%-94% of the Zn was found in the cell walls and the soluble fraction and only 6%-9% Zn was distributed in the cell organelle fraction. For NHE, about 20%-26% Zn was recovered in the cell organelle fraction. In stems, Zn distribution to the ceil wail fraction was approximately two fold greater in the HE than that in the NHE. For the hyperaccumulating ecotype of S. alfredii, the cell wall and the vacuole played a very important role in Zn tolerance and hyperaccumulation.
基金Project supported by the National Natural Science Foundation of China(No.31000935)he Fundamental Research Funds for the Central Universities(No.2012FZA6008)the Department of Science & Technology of Zhejiang Province(No.2011C22077),China
文摘The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils.Organic acid has been suggested to be involved in toxic metallic element tolerance,translocation,and accumulation in plants.The impact of exogenous organic acids on cadmium(Cd) uptake and translocation in the zinc(Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study.By the addition of organic acids,short-term(2 h) root uptake of 109 Cd increased significantly,and higher 109 Cd contents in roots and shoots were noted 24 h after uptake,when compared to controls.About 85% of the 109 Cd taken up was distributed to the shoots in plants with citric acid(CA) treatments,as compared with 75% within controls.No such effect was observed for tartaric acid(TA).Reduced growth under Cd stress was significantly alleviated by low CA.Long-term application of the two organic acids both resulted in elevated Cd in plants,but the effects varied with exposure time and levels.The results imply that CA may be involved in the processes of Cd uptake,translocation and tolerance in S.alfredii,whereas the impact of TA is mainly on the root uptake of Cd.
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 (No. 41501340)the Zhejiang Provincial Natural Science Foundation of China (No. LQ14D010002)
文摘The pollution of soils by heavy metals has dramatically increased in recent decades. Phytoextraction is a technology that extracts elements from polluted soils using hyperaccumulator plants. The selection of appropriate plant materials is an important factor for successful phytoextraction in field. A field study was conducted to compare the efficiency of six high-biomass forage species in their phytoextraction of heavy metals(Cd, Pb, and Zn) from contaminated soil under two harvesting strategies(double harvesting or single harvesting). Among the tested plants, amaranth accumulated the greatest amounts of Cd and Zn, whereas Rumex K^(-1) had the highest amount of Pb in the shoot under both double and single harvesting. Furthermore, double harvesting significantly increased the shoot biomass of amaranth, sweet sorghum and sudangrass and resulted in higher heavy metal contents in the shoot. Under double harvesting, the total amounts of extracted Cd, Pb and Zn(i.e., in the first plus second crops) for amaranth were 945, 2 650 and 12 400 g ha^(-1), respectively, the highest recorded among the six plant species. The present results indicate that amaranth has great potential for the phytoextraction of Cd from contaminated soils. In addition, the double harvesting method is likely to increase phytoextraction efficiency in practice.
文摘Commelina communis L. growing over some new copper mining wastelands at Bijiashan, Tongling City of Anhui Province, China, was found to be a copper hyperaccumulator. Its copper concentrations were 2707-6159 (4439±2434) mg kg-1, 369-831 (731±142) mg kg-1, and 429-587 (547±57) mg kg-1, respectively, in the roots, stems, and leaves. The soils supporting the growth of the species had a copper concentration ranging from 4620 to 5020 mg kg-1 and averaging 4835±262 mg kg-1, suggesting that the species could not only grow on heavily copper-contaminated soils but also accumulate extraordinarily high concentration of copper. Thus, it shows great potential in the phytoremediation of copper-contaminated soils,the restoration of mined land, geochemical prospecting, and the study of environmental pollution changes.
基金financially supported by the Special Fund of Shaanxi Education Department (18JK0172)the Initial Funding of Talent in Shaanxi University of Technology (SLGQD201702)
文摘Heavy metals are widely distributed contaminants in natural environments and their potential threats to human health have attracted worldwide concerns due to the food chain. Therefore, great efforts have been made to reduce them to a safe level in soil. Compared with the traditional methods, the method using plants to remove them has been accepted as a feasible and efficient way. Herein, the geochemical behavior of heavy metals and the restoration methods with phytoremediation were reviewed. In addition, issues on heavy metal speciation as well as its influencing factors, phytoremediation mechanism, phytoremediation effect and vegetation selection principle used for phytoremediation were discussed.
