Variation in community structure of arbuscular mycorrhizal fungi associated with a Cu tolerant plant—Elsholtzia splendens

Little is known about the characteristics of arbuscular mycorrhizal fungi (AMF) community in the roots of host plants growing on heavy metal contaminated sites. The objectives of this study were to examine the community structure of AMF associated with the roots of a copper (Cu) tolerant plant—Elsholtzia splendens in a Cu mining area in southeastern Anhui Province, China. Molecular techniques were used to analyze AMF community composition and phylogenetic relationship in E. splendens roots sampled from three Cu mine spoils and two adjacent reference areas. Results obtained showed that root colonization and AMF diversity were very low and negatively correlated with total and extractable Cu concentrations. All the DNA sequences recovered belonged to the genus of Glomus. The principal component analysis (PCA) revealed that the AMF community composition varied remarkably among different sites and was related closely to soil properties, especially Cu concentrations. The distribution pattern of AMF species in various sites suggested the degree of AMF tolerance to Cu contamination. The unique AMF species that presented exclusively in heavily contaminated sites need to be further examined for potential application in phytoremediation of metal contaminated soils.     

重金属污染土壤的螯合剂诱导植物修复研究进展

植物修复作为一种生态友好型原位绿色修复技术成为重金属污染土壤修复研究的热点。然而,目前最具有推广价值的超积累植物因生物量低、生长缓慢、对重金属的积累具有专一性等缺点,大大限制了植物修复技术在重金属污染尤其是复合重金属污染土壤治理方面的推广应用。利用生长速度快、生物量大的普通植物借助其它技术辅助的联合植物修复便成了有效可行的替代途径和研究焦点。近年来,金属螯合剂诱导的化学-植物联合修复技术备受关注。本文综述了螯合剂诱导植物修复技术的研究进展、修复机理和目前存在的问题,并对该项技术的未来研究方向给予了展望。     

黑麦草生长及根系形态对土壤Cd，Pb与石油污染的响应

[目的] 研究不同污染条件下黑麦草生理指标的动态变化,为植物修复污染土壤提供初步理论基础。[方法] 通过室内试验模拟不同类型的土壤污染。设置4个处理,未污染土壤+黑麦草（SH）、重金属污染土壤（500 mg/kg Pb²⁺和50 mg/kg Cd²⁺）+黑麦草（SGH）、石油污染土壤（1 000 mg/kg石油）+黑麦草（SPH）、石油和重金属复合污染土壤（500 mg/kg Pb²⁺,50 mg/kg Cd²⁺和1 000 mg/kg石油）+黑麦草（SPGH）,采用WINRHIZO根系分析系统测量根系形态指标,用分光光度计测量叶片色素指标,研究不同类型土壤污染对黑麦草生长的影响。[结果] 3种不同类型的污染土壤均不同程度地刺激了黑麦草根系的生长。与未污染处理相比,在20 d时,石油重金属复合处理下的黑麦草根系的根长、根表面积、根体积、根直径分别增加了88.10%,148.60%,221.90%,32.20%。与未污染相比,随着培养时间的增加各污染处理的地下生物量呈现出先增加后减少的趋势,地上生物量均低于未污染处理,且在第10,40,80 d时,复合污染处理的地上生物量最小,较未污染处理分别降低了34.68%,45.42%,58.05%。80 d时,重金属污染处理、石油污染处理和石油重金属复合污染处理的黑麦草叶绿素含量显著低于未污染处理,分别降低了26.84%,44.82%和47.02%。[结论] 不同污染物都可以促进黑麦草根系形态发育,降低黑麦草的生物量及色素含量;石油重金属复合处理对黑麦草的生长影响最大,石油污染处理次之。基于不同污染物对黑麦草根系形态及生长影响的差异,在今后植物修复土壤污染过程中,可添加一些生长调节物质来缓解污染对植物的毒害作用,提高植物生物量及增强相关生理功能,提升污染土壤修复效果。     

Molecular community analysis of arbuscular mycorrhizal fungi associated with five selected plant species from heavy metal polluted soils

Arbuscular mycorrhizal fungi (AMF) are known to play an important role in plant tolerance to heavy metals (HMs) stress. This study aimed to understand the diversity of AMF communities associated with five selected plant species (Phytolacca americana, Rehmannia glutinosa, Perilla frutescens, Litsea cubeba and Dysphania ambrosioides) from severely HMs polluted soils in Dabaoshan Mine region, China, using molecular methods. Plant roots and rhizospheric soils were sampled from four sites, respectively. Targeting the fungal small subunit (SSU) rRNA gene, PCR-denaturing gradient gel electrophoresis (DGGE) analysis indicated that varied AMF communities colonized different plant species, and the AMF communities in rhizospheric soils were different from those in plant roots. Total six SSU rRNA gene clone libraries including four root samples and two rhizospheric soil samples were constructed. Screening clone libraries by DGGE and sequence analysis revealed that Glomus dominated all of the samples except for the roots of D. ambrosioides, while Kuklospora and Ambispora dominated the roots of D. ambrosioides and the rhizosphere of P. americana. This study indicates that diverse AMF are associated with these selected plants, and they are potentially useful to promote the phytoremediation of this HMs polluted area.     

Contribution of arbuscular mycorrhizal fungi and soil amendments to remediation of a heavy metal-contaminated soil using sweet sorghum

Owing to their potential advantages such as waste reduction, recycling, and economic attributes, fast-growing bioenergy crops have the capacity to effectively phytoremediate heavy metal-contaminated soils. However, little is known about the role of microbial and chemical amendments in phytoremediation using bioenergy crops. Here, we studied the contributions of inoculation with the arbuscular mycorrhizal fungus (AMF) Acaulospora mellea ZZ and three soil amendments, i.e., hydroxyapatite (HAP), manure, and biochar, at doses of 0.1% and 1% (weight:weight) to heavy metal phytoremediation using sweet sorghum grown on an abandoned agricultural soil, with environmentally realistic contamination (2.6 mg kg^-1 Cd, 1 796 mg kg^-1 Pb, and 1 603 mg kg^-1 Zn), in a plant growth chamber. Mycorrhizal colonization, plant biomass and metal accumulation, metal availability, and soil pH were determined in harvested seedlings 12 weeks after sowing. The results showed that root colonization by indigenous AMF decreased by 28%-46% with HAP, but increased after manure and biochar applications as compared to the no amendment control (CK). The AMF inoculation increased root colonization rates by 16%-128% and in particular, alleviated the inhibition of HAP. The remediation effects were highly dependent on the amendment type and dose. Among the three soil amendments, HAP was the most effective in promoting plant growth and phytostabilization of Cd, Pb, and Zn and phytoextraction of Cd, particularly at a dose of 1%. Compared to CK, 1% HAP decreased DTPA-extractable Cd, Pb, and Zn concentrations in soil by 31%-43%, 30%-38%, and 22%-23%, respectively. Manure and biochar also exerted positive effects on heavy metal immobilization, as indicated by lower DTPA extractability, but only the 1% manure treatment showed plant growth-promoting effect. The AMF inoculation did not affect plant growth, but increased soil pH and induced synergistic interactions with amendments on the immobilization of Cd and Pb. In conclusion, soil amendments, particularly HAP, produced positive impacts and synergistic interactions with AMF on the phytostabilization of heavy metals using sweet sorghum. Accordingly, sweet sorghum combined with soil amendments and AMF may be an effective strategy for heavy metal phytoremediation.     

Molecular diversity of arbuscular mycorrhizal fungi associated with two dominant xerophytes in a valley-type savanna,southwest China

The diversity of arbuscular mycorrhizal fungi (AMF) colonizing the roots and rhizosphere soils of Heteropogon contortus and Dodonaea viscose growing in a valley-type savanna, southwest China, were analyzed by the large subunit ribosomal RNA genes (LSU). A total of 547 AMF sequences were screened for establishment of four clone libraries. Phylogenetic analysis revealed that the sequences clustered in at least 8 discrete sequence groups, all belonging to the genus Glomus. Among the Glomus spp., Glo 1 (GlGr A) and Glo 7 (GlGr B) were the most common in all root and soil samples of the two xerophytes, accounting for 42% and 33% of all screened clones, respectively. The ∫-LIBSHUFF analysis revealed that the composition of AMF communities associated with the two xerophytic hosts varied greatly both in roots and their rhizosphere soils.     

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

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

Phytoextraction of Pb and Cd from a contaminated agricultural soil using different EDTA application regimes: Laboratory versus field scale measures of efficiency

Enhanced phytoextraction of heavy metals using chelating agents and agricultural crops is widely discussed as a remediation technique for agricultural soils contaminated with low mobile heavy metals. In this study, phytoextraction efficiency of Zea mays after single and split applications of EDTA was tested on the laboratory and the field scale. EDTA effectively increased the mobility of target heavy metals (Pb and Cd) in the soil solution. Split applications provided generally lower water-soluble levels of Pb and Cd both in the pot and the field experiment. Therefore, the risk of groundwater contamination may be reduced after split applications. Higher Pb and Cd mobilisation after single applications increased plant stress, phytotoxicity and reduced plant dry above-ground biomass production compared to corresponding split doses. Single doses enhanced plant uptake of Pb and Cd and the phytoremediation efficiency compared to corresponding split doses. Results of plant dry above-ground biomass and heavy metal uptake obtained from the pot experiment could be to some extent verified in the field experiment. Plant uptake of Pb and Cd was lower and biomass production dropped after EDTA additions in the field experiment. Remediation factors in the field experiment were in general significantly lower than in the pot experiment mainly due to the much higher mass of soil per plant under field conditions. This highlights the limitations when going from the lab to the field scale. The low phytoremediation efficiency in the field and the mobilisation of high amounts of Pb and Cd down the soil profile may make the use of EDTA and Z. mays not suitable for the remediation of severely heavy metal contaminated soils in a reasonable time frame and may result in substantial groundwater pollution under used crop management.     

Spent mushroom compost enhances plant response and phytoremediation of heavy metal polluted soil

Background: Stimulatory efficacy of spent mushroom compost (SMC) cannot be overemphasized. Aims: In this study, the effect of SMC on phytoremediation and plant's response to heavy metal polluted soil was investigated and suggested for the establishment of feasible soil remediation. Methods: Heavy metal polluted soil (80 kg) was sterilized at 121°C in soil sterilizer for 30 min and repeated four more times to remove microbial interference. Five kg of soil was packed into pots supplemented with SMC of Pleurotus ostreatus at different concentrations of 10, 20, 30, and 40%, and control (no SMC), and used to grow the test plant (Megathyrsus maximus commonly known as Guinea grass) for 90 d. Effect of SMC treatments on chemical characteristics of the soil was determined through soil analysis before and after the experiment. Plant response to SMC in polluted soils was studied by observing root proliferation, plant growth, and biomass. Results: The results suggest that SMC treatment modified soil chemical characteristics, the germination index (GI), plant growth, and phytoremediation potential. The soil's pH increased from 4.3 in control to 6.8 both in 40 and 30% SMC treatments; also the soil's nutrients, cation exchange capacity (CEC), and GI improved with incremental increase in SMC treatments, while the heavy metal removal was best observed at 40 and 30% treatments. In addition, the bio‐stimulatory effect of SMC was confirmed on guinea grass root proliferation, growth, phytomass and its phytoremediation potentials on heavy metals. Conclusions: The SMC is therefore suggested for soil stimulation to improve plant's growth and phytoremediation.     

共培养对土壤重金属污染植物修复的调控作用

A co-culture of two plant materials, Astragalus sinicus L., a leguminous plant with concomitant nodules, and Elsholtzia splendens Naki-a Cu accumulator, along with treatments of a chelating agent (EDTA), root excretions (citric acid), and a control with E. splendens only were used to compare the mobility of heavy metals in chelating agents with a co-culture and to determine the potential for co-culture phytoremediation in heavy metal contaminated soils. The root uptake for Cu, Zn, and Pb in all treatments was significantly greater (P < 0.05) than that of the control treatment. However with translocation in the shoots, only Cu, Zn, and Pb in plants grown with the EDTA treatment and Zn in plants co-cropped with the A. sinicus treatment increased significantly (P < 0.05). In addition, when a co-culture in soils with heavy and moderate contamination was compared, for roots in moderately contaminated soils only Zn concentration was significantly less (P < 0.05) than that of heavily contaminated soils, however, Cu, Zn, and Pb concentrations of shoots were all significantly lower (P < 0.05). Overall, this "co-culture engineering" could be as effective as or even more effective than chelating agents, thereby preventing plant metal toxicity and metal leaching in soils as was usually observed in chelate-enhanced phytoremediation.     

香薷属植物在重金属修复中的应用进展

香薷属植物应用于重金属修复经历了矿区植物资源调查和比较、室内模拟研究、田间规模修复以及修复后处置研究,已经初步形成一个植物修复技术的完整体系。在现有技术条件下,把生态修复模式、品种驯化及诱导剂"配方"应用到香薷属植物修复土壤重金属污染对提高修复效率具有重要意义。     

Effect of fertilization of a biochar and compost amended technosol: Consequence on Ailanthus altissima growth and As- and Pb-specific root sorption

The remediation of metal(loid) polluted soil using plants (i.e. phytoremediation) often requires the application of amendments, as well as chemical fertilizer. However, such fertilizers can have negative effects when applied alone and can thus be applied together with other organic amendments to diminish this negative effect. Finally, plants to be used in phytoremediation should be selected based on their adaptive capacity and tolerance to poor and highly contaminated soils, characteristics that possesses Ailanthus altissima. The objective of this study was to evaluate the effects of osmocote fertilization on the amended mining technosol properties and plant growth parameters, as well as to study the accumulation pattern of As and Pb in plant roots. Results showed that osmocote ameliorated soil conditions, but increased Pb mobility. It also greatly improved plant growth. Finally, different behaviours of metal(loid) accumulation were observed in the roots: As was absorbed mainly in the roots because of its similarity with P, with very low amounts in the leaves, whereas Pb was adsorbed mainly on the root surface, with lesser proportion absorbed inside the root system.     

Effects of multiple heavy metal contamination and repeated phytoextraction by Sedum plumbizincicola on soil microbial properties

The threat of heavy metal contamination to food and human health in south and east China has become a public concern as industrial development continues. The aims of this study were to investigate the influence of repeated phytoextraction over a two-year period by successive crops of the Zn and Cd hyperaccumulator Sedum plumbizincicola on multiple metal contaminated soils and to assess recovery of soil quality. Total and NH₄OAc-extractable Zn and Cd concentrations were significantly reduced in planted soils compared to unplanted soils. Microbial biomass C (C_mic), basal respiration and microbial quotient (qM) were significantly and positively correlated and soil metabolic quotient (qCO₂) was negatively correlated with heavy metal concentrations in unplanted soils (P < 0.05). However, C_mic, basal respiration and qM values increased significantly after phytoremediation by five crops over two years compared to unplanted soil. Urease, β-glucosidase, neutral phosphatase and arylsulfatase activities also increased significantly with decreasing heavy metal contents and hydrolase activity was enhanced in planted soil (P < 0.05) compared to the unplanted control. The data indicate the capacity of S. plumbizincicola to extract Zn and Cd from contaminated soil and also that phytoremediation had beneficial effects on soil microbial and hydrolase activities, with the metal phytoextraction procedure restoring soil quality.     

丛枝菌根真菌菌丝对土壤微生物群落结构及 多氯联苯降解的影响

以摩西球囊霉(Glomus mosseae)为供试菌种,在光照培养箱内利用分室根箱研究丛枝菌根真菌菌丝对多氯联苯(polychlorinated biphenyls,PCBs)污染土壤的修复效应及其机理。试验设置接种丛枝菌根真菌的处理以及不接种的对照,选用美国南瓜(Cucurbita pepo L.)为供试植物,在南瓜生长40天后将接种菌根真菌处理的菌丝室土壤从尼龙网向外水平分为4层取样,测定PCBs及磷脂脂肪酸含量。结果表明:菌丝可以穿越尼龙网影响菌丝室土壤,且距离尼龙网越远菌丝量越低;菌丝显著促进了土壤微生物量(P0.05),并改变了不同土层土壤微生物群落结构;接种菌根真菌处理各土层PCBs降解率为35.67%~57.39%,均显著高于对照的17.31%,相关分析结果表明土壤三氯、四氯联苯以及PCBs总量与菌丝量呈极显著负相关(P0.01);菌丝际土壤微生物量,特别是细菌生物量与土壤三氯联苯含量呈显著负相关(P0.05)。可见,菌丝通过影响菌丝际土壤微生物群落结构及生物量,促进三氯及四氯联苯降解,从而提高土壤PCBs修复效率。     

Glyphosate reduces spore viability and root colonization of arbuscular mycorrhizal fungi

Glyphosate is the most widely used herbicide in the world, but its effects on non-target organisms, such as arbuscular mycorrhizal fungi (AMF), are unclear. No studies have been found that made reference to effects of glyphosate on AMF spore viability despite its importance as a source of propagules for the perpetuation and spread of AMF in the system. The objective of this study was to evaluate the effect of glyphosate application on AMF spore viability, and their ability to colonize roots. Soil samples were collected from a grassland area located in the Flooding Pampa region (Argentina). We evaluated three herbicide rates: 0, 0.26 and 1× recommended field rate, 10 and 30 days after application. Part of the soil from each tray was used to estimate the spore viability, and the remainder was used as substrate for growing Lolium multiflorum Lam. One month after sowing, total root colonization and percentage of arbuscules and vesicles were determined. The spore viability in herbicide untreated soils was between 5.8- and 7.7-fold higher than in treated soils. This reduction was detected even when the lower rate was applied. Root colonization was significantly lower in plants grown in glyphosate treated soil than in untreated ones. A decrease in arbuscular colonization (but not in vesicles) was found in plants grown in soils treated with the highest herbicide rate. That would indicate that symbiosis functionality was affected, given that arbuscules are the main site for host–fungus nutrient exchange. The results indicate that soil residence time of glyphosate and/or its degradation products was enough to reduce AMF spore viability and their ability to colonize roots. This decrease in propagules viability may affect plant diversity, taking into account the different degrees of mycorrhizal dependency between plant species that may coexist in grassland communities.     

根迹土壤根诱导的化学变化对植物吸收重金属的影响

It is increasingly recognized that metal bioavailability is a better indicator of the potential for phytoremediation than the total metal concentration in soils; therefore, an understanding of the inffuence of phytoremediation plants on metal dynamics at the soil-root interface is increasingly vital for the successful implementation of this remediation technique. In this study, we investigated the heavy metal and soil solution chemical changes at field moisture, after growth of either Indian mustard (Brassica juncea) or sunffower (Helianthus annuus L.), in long-term contaminated soils and the subsequent metal uptake by the selected plants. In addition, the fractions of free metal ions in soil solution were determined using the Donnan membrane technique. After plant growth soil solution pH increased by 0.2-1.4 units and dissolved organic carbon (DOC) increased by 1-99 mg L^-1 in all soils examined. Soluble Cd and Zn decreased after Indian mustard growth in all soils examined, and this was attributed to increases in soil solution pH (by 0.9 units) after plant growth. Concentrations of soluble Cu and Pb decreased in acidic soils but increased in alkaline soils. This discrepancy was likely due to a competitive effect between plant-induced pH and DOC changes on the magnitude of metal solubility. The fractions of free Cd and Zn ranged from 7.2% to 32% and 6.4% to 73%, respectively, and they generally decreased as pH and DOC increased after plant growth. Metal uptake by plants was dependant on the soil solution metal concentration, which was governed by changes in pH and DOC induced by plant exudates, rather than on the total metal concentrations. Although plant uptake also varied with metal and soil types, overall soluble metal concentrations in the rhizosphere were mainly inffuenced by root-induced changes in pH and DOC which subsequently affected the metal uptake by plants.     

Problems and prospects concerning the phytoremediation of heavy metal polluted soils: A review

The current state, problems, and prospects of phymoremediation of heavy metal polluted soils are analyzed. The main attention is paid to the phytoextraction and phytostabilization as the most widespread and alternative methods of soil phytoremediation. The efficiency of phymoremediation is related to the natural capability of plants for the accumulation and translocation of metals, their tolerance to a high content of metals, the plant biomass, and the amendments applied. The advantages and disadvantages of phytoremediation as compared to other methods of remediation of polluted soils in situ are considered. Examples of successful phytoextraction and phytomining for cleaning up of contaminated soils in Rasteburg (South Africa) and the phytostabilization of technogenic barrens nearby the copper-nickel plants in Sudbury (Ontario, Canada) and in the Kola Subarctic (Russia) are presented.     

Occurrence and infectivity of arbuscular mycorrhizal fungi in some norwegian soils influenced by heavy metals and soil properties

Mycorrhizae are ubiquitous symbiosis which can mediate uptake of some plant nutrients. In polluted soils they could be of great importance in heavy metal availability and toxicity to plants. Mycorrhizae have also been reported to protect plants against toxic metals. We investigated the occurrence and infectivity of arbuscular mycorrhizal (AM) spores as affected by heavy metal levels and other soil properties in Norwegian soils collected from heavy metal polluted, high natural background and non-polluted areas. Spore numbers, mycorrhizal infectivity and spore germination of indigenous mycorrhizal fungi and of a reference strain (Glomus mosseae) in soils showed lower values in two soils with high metal concentrations and in one soil with a low pH. Mycorrhizal infectivity was negatively correlated with extractable metals. Spore number and mycorrhizal infectivity in a soil with naturally high heavy metal content were not different to in non-polluted soils, and indigenous AM fungi appeared more tolerant to metals than those in non-polluted soils. Mycorrhizal infectivity, expressed as MSI₅₀ values, was significantly correlated (r′=0.89, P< 0.05) with the percentage of germinating G. mosseae spores in the soils. However, the number of spores per volume of soil was not significantly correlated with infectivity or spore germination of the reference strain. The spore germination method is discussed as a bioassay of heavy metal toxicity in soil.     

Rhizosphere microbial community and Zn uptake by willow (Salix purpurea L.) depend on soil sulfur concentrations in metalliferous peat soils

On numerous occasions, rhizosphere microbial activities have been identified as a key factor in metal phytoavailability to various plant species and in phytoremediation of metal-contaminated sites. For soil bioremediation efforts in heavy metal contaminated areas, microbes adapted to higher concentrations of heavy metals are required. This study was a field survey undertaken to examine rhizosphere microbial communities and biogeochemistry of soils associated with Zn accumulation by indigenous willows (Salix purpurea L.) in the naturally metalliferous peat soils located near Elba, NY. Soil and willow leaf samples were collected from seven points, at intervals 18 m apart along a willow hedgerow, on four different dates during the growing season. Soil bacterial community composition was characterized by terminal restriction fragment length polymorphism (T-RFLP) analysis and a 16S clone library was created from the rhizosphere of willows and soils containing the highest concentrations of Zn. Bacterial community composition was correlated with soil sulfate, but not with soil pH. The clone library revealed comparable phylogenetic associations to those found in other heavy metal-contaminated soils, and was dominated by affiliations within the phyla Acidobacteria (32%), and Proteobacteria (37%), and the remaining clones were associated with a wide array of phyla including Actinobacteria, Gemmatimonadetes, Planctomycetes, Verrucomicrobia, Bacteriodetes, and Cyanobacteria. Diverse microbial populations were present in both rhizosphere and bulk soils of these naturally metalliferous peat soils with community composition highly correlated to the soil sulfate cycle throughout the growing season indicative of a sulfur-oxidizing rhizosphere microbial community. Results confirm the importance of soil characterization for informing bioremediation efforts in heavy metal contaminated areas and the reciprocity that microbial communities uniquely adapted to specific conditions and heavy metals may have on an ecosystem.     

湖南冷水江锑矿区苎麻对重金属的吸收和富集特性

通过野外调查采样,分析了湖南冷水江锑矿区土壤的重金属含量,以及矿区9个采样点的苎麻对Sb、Cd、As和Pb4种重金属的吸收与富集能力及其富集特征。结果表明,矿区土壤受Sb污染严重,9个采样点Sb含量超过全国土壤背景值40～11503倍;伴生有Cd、As、Pb污染,Cd平均含量（13.08mg·kg-1）和As平均含量（82.64mg·kg-1）明显高于土壤环境质量标准的三级警戒值,Pb平均含量（71.27mg·kg-1）明显高于全国土壤背景值。苎麻叶和花混合样中的Sb最高达到1103mg·kg-1;苎麻体内的Cd含量均高于一般植物2～10倍,Cd富集系数最高为2.1,转运系数最高为3;As富集系数最高为1.04,转运系数最高为12.42;苎麻地上部对重金属迁移能力较强,当季对Sb、Cd、As迁移量分别达796.55、11.20和31.34mg·m-2。本研究说明苎麻对复合重金属具有一定的耐性,为复合污染植物修复提供了一种新的种质资源。