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1.
Abstract

This greenhouse study examined the root characteristics (biomass, length, area, and diameter) and root uptake efficiency of Pteris vittata, an arsenic (As) hyperaccumulator and Nephrolepis exaltata, not an As hyperaccumulator, in relation to plant uptake of As and nutrients in an As‐contaminated and a control soil. After 8 weeks of growth, on a per plant basis, P. vittata accumulated 7.3–8.8 g of biomass and removed 2.51 mg of As from the As‐contaminated soil compared to 2.4–2.7 g of biomass and 0.09 mg of As for N. exaltata. This was partially because P. vittata developed a more extensive root system, 2.4–3.8 times greater (biomass, length, and area), and possessed a greater proportion of fine roots than N. exaltata. In addition, the As root‐uptake efficiency (defined as As concentrations in plant tissue per unit root) for fronds of P. vittata was 15–23 times greater than that of N. exaltata in both soils. Whereas N. exaltata removed phosphorus (P) more efficiently from the soils, P. vittata removed As more efficiently. The larger root biomass coupled with more efficient root‐uptake systems for As may have contributed to As hyperaccumulation by P. vittata.  相似文献   

2.
Plant age affects its elemental uptake and biomass accumulation, which is important for the application of plants in phytoextraction. In this research, we evaluated the effects of plant age on arsenic accumulation by arsenic hyperaccumulator Pteris vittata after growing in an arsenic-contaminated soil for 8 weeks. The study used a completely randomized design consisting of four plant ages (2, 4, 10 and 16 months) with four replications each. While the fronds of the 2 month old plants contained 36% more arsenic than those of the 4 and 16 month old plants, they were lower in roots. After 8 weeks of growth, the final frond biomass increased by 39, 6.9, 2.0 and 1.1 times compared to the initial frond biomass, from youngest to oldest, respectively. Higher phosphorus and iron accumulation in the roots of older plants may have affected the plant’s efficiency to bioconcentrate and transfer arsenic from the roots to the fronds. Greater metabolic activity and higher rate of biomass production lead to higher As accumulation and removal by young plants. This research demonstrated that the use of young plants can be an effective strategy to reduce the time to remediate an As-contaminated site.  相似文献   

3.
Although Pteris vittata L. can occur on arsenic (As)–contaminated soils and uncontaminated soils, variation in As accumulation among nonmetallicolous and metallicolous populations and impacts of heavy metals in soils on As accumulation in the nonmetallicolous and metallicolous populations have not been fully explored. Five populations of P. vittata were collected from different field sites, and sporelings (four or five fonds) were used to further investigate the pattern of As accumulation. The results of pot trials showed that three nonmetallicolous populations of P. vittata possessed an obviously greater growth rate than the two metallicolous populations. The nonmetallicolous populations also accumulated significantly greater (P < 0.05) As than the metallicolous populations, regardless of the presence or absence of lead (Pb) and zinc (Zn). In addition, Pb and Zn in soils decreased As accumulation in P. vittata. The present results suggested that As removal can be greatly enhanced by the judicious selection of populations of P. vittata.  相似文献   

4.
《Journal of plant nutrition》2013,36(7):1227-1242
Abstract

Uptake of arsenic (As) and its distribution in Chinese Brake fern (Pteris vittata L.), an As hyperaccumulator, and Boston fern (Nephrolepis exaltata L.), a nonhyperaccumulator, in the presence of phosphorus (P), were characterized by employing a hydroponic experiment with a complete three-factorial design. Two levels of As (100 and 1000 µM) and four levels of P (0, 100, 500, and 1000 µM) were used in this study. Arsenic uptake rates on the basis of root fresh weight for the two ferns were similar at low As concentration (100 µM). At high As concentration (1000 µM), however, As uptake rates (373–987 nmol g?1 f wt h?1) of P. vittata were significantly greater than those of N. exaltata (164–459 nmol g?1 f wt h?1). In both ferns, addition of P reduced their As uptake rate as well as accumulation. Pteris vittata had a greater As TF (Translocation factor = concentration ratio of fronds to roots) than N. exaltata. On the contrary, N. exaltata displayed a greater P TF than P. vittata. As a result, high P/As ratio was observed in the roots of P. vittata, whereas high P/As ratio was observed in the fronds of N. exaltata. The study illustrated that As hyperaccumulation by P. vittata may be facilitated by its high As influx rate and its high molar P/As ratio in the roots resulting from both high As TF and low P TF.  相似文献   

5.
Arsenic (As) is a semimetallic element that is notorious for its toxicity and carcinogenicity. Arsenic can be removed by some ferns. The objectives of this study were to investigate the ability of Pteris vittata L. (Pteridophyta) and Phlebodium aureum (L.) J. Sm. (Polypodiaceae) to absorb inorganic As, in the form of arsenate and arsenite. The removal of As by ferns was observed at varying anion concentrations and As solubility in the absorbing plant. Results obtained with ferns on As‐contaminated soil indicate that redox potential and iron (Fe) presence affected the solubility of As and the absorption capacity of ferns. Upon reduction to ?200 mV, the soluble As content increased to 400 mV. The results indicate that Fe oxides and the influence of redox potential strongly affect As absorption. Under nonreducing conditions, Phlebodium aureum did not remove As as well as Pteris vittata. Under more reducing conditions (?200 to 0 mV) and under similar soil conditions, the results show that the both ferns remove As.  相似文献   

6.
Arsenic (As) toxicity has become a global concern because of the ever‐increasing contamination of water, soil, and crops in many regions of the world. Although most plants are susceptible to As, some ferns are resistant to it and can accumulate As. In this study, four species of ferns, Asplenium nidus (AN), Pteris umbrosia (PU), Polypodium vulgare (PV), and Pteris cretica (PC), were screened for their ability to tolerate and hyperaccumulate As. Ferns were exposed to 120 mg As kg?1 as sodium arsenate (Na2HAsO4) for 50 days under natural sunlight in greenhouse conditions, and the fronds and roots were analyzed for As speciation and selected macronutrients [potassium (K) and phosphorus (P)]. The species of ferns varied widely in their abilities to transport As to the fronds (ranged from 164 to 4820 mg kg?1 DW) with the greatest frond As concentration found in PU (4820 mg kg?1). The distribution of soil As fractions indicated that As was mostly bound carbonate (carb) (32.4%) and in the residual fractions (45.1%). Chemical fractionation of As‐spiked soil indicated that the greatest reduction in soil As after growing was in carb As form. Arsenic speciation analysis shows that >82% of the total As in the aboveground biomass is present as the reduced form of As, arsenite [As(III)], which is considered to be the more toxic form. However, in roots, only 60% of the As is present as As(III). Furthermore, among the four species of ferns, PU is the most promising to be used in the remediation of the affected area. Therefore, it is possible to use PU to remediate As‐contaminated soils by repeatedly harvesting its fronds.  相似文献   

7.
A laboratory study was conducted to evaluate the availability of arsenic (As) to roots in nine soils from five fields in Tuscany (Italy). Concentrations of As in soils range from 200 to 1200 mg kg?1 as a result of human activities and natural deposition. In a first stage, potentially root‐available As and the risk of crop uptake were estimated using the diffusion gradient in thin films (DGT) technique. In a second stage, a glasshouse experiment was performed to compare As depletion in the rhizosphere by the hyperaccumulator Pteris vittata (ladder brake), and by the test plant Agrostis capillaris (colonial bentgrass). In this stage, DGT results were supported by a sequential extraction procedure. The main objectives were to study the root availability of As in old, contaminated soils and the modification of the available pool size over time. The phytoextraction efficiency of Pteris vittata as applied to this case study was also investigated. In all samples, concentrations of total and potentially root‐available As in soil solution were small compared with total As in soil (approximately 0.0003–0.03%, corresponding to 3.5–350 μg l?1, respectively). There was also little re‐supply of As from the solid phase to the soil solution. In the rhizosphere, despite uptake by Pteris and Agrostis, total and root available As in solution were sustained over time. It appeared that plants induced a re‐supply of As from the solid phase. Despite the uptake and translocation of As by Pteris (50.7 mg kg?1 and 6.6 mg As kg?1 in fronds and roots, respectively) together with plant biomass (17.2 g per plant), the success of phytoextraction appears unlikely. The results obtained demonstrated the sensitivity of DGT to root‐induced changes in soil and the suitability of the technique as an easy‐to‐use tool to predict assimilation by plants.  相似文献   

8.
Soils used for rice (Oryza sativa L.) cultivation in some areas contain high concentrations of arsenic (As) due to irrigation with groundwater containing As and intensive use of agrochemicals or industrial residues containing As. To restrict rice uptake of As in these soils, approaches to reduce As input and bioavailability must be considered. One approach to reduce As input into rice soils or uptake by rice is cultivating rice under aerobic, intermittent flooding, or alternate wetting and drying (AWD) conditions, rather than in submerged soils, or use of irrigation water low in As. For reducing As bioavailability in soil, aerobic or AWD rice culture and application of biochar, sulfur (S), and/or rice polish to soil are promising. Moreover, use of As-hyperaccumulating plant species (e.g., Pteris vittata L.) in rotation or combinations with favourable plant species (e.g., Azolla, Chlorella, or Nannochloropsis species) can also be promoted, in addition to using rice cultivars that are tolerant to As. Though applications of high doses of phosphorus (P), iron (Fe), and silicon (Si) fertilizers have shown promise in many instances, these methods have to be practiced carefully, because negative effects have also been reported, although such incidents are rare. Major factors affecting As speciation and bioavailability in soil are chemical properties such as redox status, pH, and Fe, P, Si, and S concentrations, physical properties such as texture and organic matter, and biological properties such as methylation activity by soil microorganisms. However, as many of these factors interact, long-term examination under field conditions is needed before measures are recommended for and implemented in farmers' fields.  相似文献   

9.
Experiments were conducted to evaluate the arsenic toxicity, its accumulation and phytoremediation potential of bean plants (Phaseolus vulgaris) grown in soils contaminated with different species of arsenic such as arsenite (As(III)), arsenate (As(V)) and dimethylarsinic acid (DMA). Bean plants were grown in soils amended by aqueous solutions of 20 and 50 mg kg?1 of As (III), As(V) or DMA. Arsenic species negatively affected the yield and growth of the plant. The study demonstrated arsenic accumulation in the plant parts. The concentration of arsenic compounds in the shoots decreased in the order arsenate > arsenite > dimethylarsinic acid while in the roots as arsenite > arsenate > dimethylarsinic acid. Most arsenic is accumulated in the roots with limited transfer to shoots. Thus, bean plants can be considered as an arsenic excluder and has the potential for phytostabilization of arsenic contaminated sites. The study also reveals that removal of arsenic by boiling the vegetables with excess of water is not possible.  相似文献   

10.
Effects of inoculation with three different arbuscular mycorrhizal (AM) fungi (Glomus etunicatum, Glomus constrictum, and Glomus mosseae) on arsenic (As) accumulation by maize were investigated by using soil spiked with As at rates of 0, 25, 50, and 100 mg kg?1. The root colonization rates by the three fungi were significantly different (G. mosseae > G. etunicatum > G. constrictum) and decreased markedly with increasing As concentration in the soil. Inoculation with G. etunicatum or G. mosseae increased maize biomass and phosphorus (P) accumulation (G. mosseae > G. etunicatum) and reduced As accumulation in shoots (G. mosseae ≈ G. etunicatum), whereas inoculation with G. constrictum had little effect on these parameters. Inoculation with G. mosseae produced greater biomass and P uptake and less shoot As accumulation, and therefore it may be a promising approach to reduce As translocation from contaminated soils to plants.  相似文献   

11.
A greenhouse experiment was conducted to investigate the effect of phytoextraction by Chinese brake fern (Pteris vittata L.) on microbial activity and biomass in arsenic-contaminated soil (naturally occurring arsenic-contaminated soils of West Bengal, India). P. vittata was grown for two successive growing cycles (4 months each) with two phosphate sources (di-ammonium phosphate (DAP) and single superphosphate (SSP)). After phytoextraction by P. vittata, the rhizosphere soils were analyzed for microbial biomass C (MBC), C mineralization (Cmin), dehydrogenase activity (DHA), phosphomonoesterase activities, and aryl sulphatase activity. All enzyme activities increased after two successive growing cycles of P. vittata as compared to one growing cycle and unplanted control. The arsenic (As) phytoextraction by this fern also increased the MBC by 34 %, Cmin by 63 %, DHA by 38 %, acid phosphomonoesterase activity by 30 %, alkaline phosphomonoesterase activity by 6 %, and aryl-sulphatase activity by 33 % with two successive growing cycles over unplanted control. The di-ammonium phosphate was better as compared to single super phosphate for enhancing microbiological and biochemical parameters except phosphomonoesterase activities.  相似文献   

12.
Abstract

Athyrium yokoscense, a type of fern that grows vigorously in mining areas in Japan, is well known as a Cd hyperaccumulator as well as a Cu, Pb and Zn tolerant plant. However, no information is available on As accumulation of A. yokoscense, although it often grows on soils containing high levels of both heavy metals and As. In this study, young ferns collected from a mine area were grown in media containing As-spiked soils or mine soil in a greenhouse for 21 weeks. Athyrium yokosense was highly tolerant to arsenate and survived in soils containing up to 500 mg As (V) kg?1. The addition of 100 mg As (V) kg?1 resulted in the highest fern biomass (1.95 g plant?1) among As-spiked soils. Although the As concentration of the fern was lower than other As hyperaccumulators, such as Pteris vittata, A. yokoscense could hyperaccumulate As in mature and old fronds. Arsenic was accumulated most efficiently in old fronds (922 mg kg?1) in the media containing 5 mg As (III) kg?1. Moreover, higher As accumulation was found in the roots of the ferns, with a range from 506 to 2,192 mg kg?1. In addition, in the mine soil with elevated concentrations of As and heavy metals, A. yokoscense not only hyperaccumulated As (242 mg As kg?1 in old fronds), but also accumulated Cd, Pb, Cu and Zn at concentrations much higher than those reported for other terrestrial plants. Athyrium yokoscense accumulated Cd mostly in fronds in high concentrations, up to 1095 mg kg?1, while it accumulated Cu, Zn and Pb mainly in the roots and the concentrations were 375, 2040 and 1165 mg kg?1, respectively.  相似文献   

13.
砷污染土壤的蜈蚣草修复研究进展   总被引：5，自引：1，他引：4  
潘志明  邓天龙 《土壤》2007,39(3):341-346
本文评述了As污染土壤的蜈蚣草植物修复及其对As的解毒机制的研究进展,内容着重包括蜈蚣草对As的富集特征,As在蜈蚣草中的赋存形态、迁移及其转化,土壤以及土壤中P、Ca和K等元素对蜈蚣草吸收、转运As的影响等方面。  相似文献   

14.
High As groundwater normally contained high concentrations of Cl? and HCO 3 ? . This study examined the effects of Cl?, HCO 3 ? , and As species on As uptake by hyperaccumulator Pteris vittata. Plants were exposed hydroponically to 5.0?mg/L As(III) or As(V) in the presence of 0, 0.5, 1, 2, 5, 10, and 20?mM of Cl? or HCO 3 ? for 10?days. Addition of high Cl? concentrations (>10?mM) slightly inhibited P. vittata growth (biomass), while generally had no significant effect on plant As uptake. High solution pH resulted in reduced plant growth and As uptake, which attributed to the inhibitory effects in HCO 3 ? treatments with the high pH of the high HCO 3 ? concentration. It was speculated that addition of HCO 3 ? (<20?mM) would have no significant effect on plant growth and As uptake. The inhibitory effect of HCO 3 ? on As translocation was less apparent in the As(III) solutions than the As(V) solutions. For the high As groundwater with As(III) as the predominant species, high pH, instead of high concentrations HCO 3 ? and Cl?, was expected to inhibit As uptake. The results suggested that optimum plant growth and maximum As hyperaccumulation could be achieved by adjusting solution pH in the growth media (around 7.2).  相似文献   

15.
Abstract

The degree of antimony (Sb) and arsenic (As) pollution and their bioavailability in mining‐affected grassland soils were determined. Antimony and As concentrations in aboveground parts of plants, collected in three consecutive years, were measured to investigate their uptake capacity, food chain contamination, and ecological risks. Total Sb and As contents in soils ranged from 60 to 230 mg/kg and from 42 to 4530 mg/kg, respectively, indicating a high degree of pollution of soils. The mobile fractions of Sb (0.02–0.27% of the total Sb content) and As (0.02–0.70% of the total As content) in soils, which reflect the plant‐available portion, are extremely low compared to total Sb and As contents in soils. The Sb and As contents in plants were also very low in both study areas. This lower accumulation of Sb and As in the plants is attributed to the low bioavailability of Sb and As in mine soils. Antimony and As contents in some plants were lower than the controls, and the concentrations in some plants were slightly higher than the normal grass mean level but were less than the phytotoxic or toxic levels for human or livestock consumption. The results of this study demonstrate that the plants growing in these mining areas, which have evolved As and Sb tolerance and detoxification capacity, can be cultivated to phytostabilize the metalloid‐contaminated mining sites.  相似文献   

16.
The effects of inoculation with two AM fungi (M1, Glomus caledonium; M2, Glomus spp. and Acaulospora spp.) and a fungivorous nematode Aphelenchoides sp. on growth and arsenic (As) uptake of Nicotiana tabacum L. were investigated in soils contaminated with a range of As. The reproduction of Aphelenchoides sp. was triggered by the co-inoculation of AM fungi regardless of AM fungal isolates and As levels. Stimulative effects of Aphelenchoides sp. on the development of mycorrhiza, slightly different between two AM fungi, were found particularly at the lowest As level. Irrespective of mycorrhizal inoculi, increasing soil As level decreased plant growth, but increased plant As uptake. Co-inoculation of AM fungi and Aphelenchoides sp. led plants to achieving further growth and greater As accumulation at the lowest As level. Results showed that the interactions between AM fungi and fungivorous nematodes were important in plant As tolerance and phytoextraction at low level As-polluted soil.  相似文献   

17.
Because crop uptake of arsenic from soils poses a human health concern, this study examines the effect of plant species, neighborhood, and planting density on arsenic uptake by brassicas grown with companion crops. At a field site contaminated by arsenic and lead, we measured arsenic uptake in arugula (Eruca sativa) and collards (Brassica oleracea var. acephala) grown in arrangements varying in species diversity and density. We further tested the effect of species diversity on arsenic uptake in two greenhouse experiments with arsenic-spiked potting soil, one test using brassicaceous plants with intercropped pairs of arugula, collards, and kale (B. oleracea var. acephala). The other had intercropped pairs of arugula, lettuce (Lactuca sativa), and marigold (Tagetes patula). Arugula in all cropping arrangements accumulated the highest and most variable concentrations of arsenic compared to other species, with neither species diversity in the companion crops nor planting density affecting arsenic uptake. We observed increased phosphorus and sulfur uptake by arugula exposed to soil arsenic in the greenhouse brassica intercropping experiments, a result that may be explained by a biological response to arsenic or competition of arsenate with phosphate and sulfate for adsorption sites in the soil. Arsenic uptake was largely independent of plant-plant facilitation effects sometimes reported for other elements, possibly because of strong buffering of the bioavailable fraction of arsenic in the soils tested.  相似文献   

18.
Heavy metal accumulation in plants on Mn Mine tailings   总被引：7，自引：0，他引：7  
The profile distribution of β-gulcosidase activity in twelve typical paddy soil profiles with high productivity in the Taihu Lake region of China were investigated. Activities of β-gulcosidase in the plow layers were in the range of 52.68- 137.02μg PNP g^-1 soil h^-1 with a mean of 89.22μg PNP g^-1 soil h^-1. However, most plow layers ranged from 70 to 110 μg PNP g^-1 soil h^-1. The profile distribution of β-gulcosidase activity in the 12 soil profiles decreased rapidly with soil depth, with activity at the 60 cm depth only about 10% of that in the surface layers （0-15 cm or 0-20 cm）. In these soil profiles, β-gulcosidase activity was significantly positively correlated with soll organic carbon and arylsulphatase activity. Meanwhile, a significantly negative correlation was shown between β-gulcosidase activity and soil pH.  相似文献   

19.

Purpose

Although arsenic (As) hyperaccumulation is a constitutive property for Pteris vittata, there is intraspecific variation in As accumulation among metallicolous (from As-contaminated soils) and nonmetallicolous populations (from uncontaminated soils) and the related mechanisms is still not clear.

Materials and methods

Pot trials, hydroponic culture, and manual simulation were conducted to investigate the roles of arsenate reductase and root exudates in accumulating As in P. vittata, which were collected from two uncontaminated sites including Sun Yat-sen University campus, Guangdong Province (ZD), and a botanical garden in Guangxi Academy of Forestry Sciences, Nanning City, Guangxi Province (NN), and two As and Pb/Zn mining and/or smelting sites located in Shaoguan of Guangdong Province (SG) and Guiyang of Hunan Province (GY).

Results and discussion

The nonmetallicolous populations (ZD and NN) possessed more efficient uptake of arsenate and arsenite than the metallicolous populations (SG and GY). There were significant (p?<?0.05) difference in arsenate reductase activities in roots among the four populations of P. vittata and that the higher arsenate reductase activities were recorded in the nonmetallicolous populations (110 nkat mg?1 protein for ZD, 160 nkat mg?1 protein for NN) compared with the metallicolous populations (62.9 nkat mg?1 protein for SG, 78.1 nkat mg?1 protein for GY). Root exudates from the nonmetallicolous population (NN) and the metallicolous population (GY) of P. vittata contained similar compositions of organic acids including oxalic, malic, and succinic acids, of which oxalate were dominant (>?67%). The NN population exuded 4.23 times more oxalate than the SG population. Root exudates from the NN population mobilized significantly (p?<?0.05) more As from As-contaminated soils than those from the SG population, of which oxalate had the most effective in As mobilization.

Conclusions

The present study suggests that higher arsenate reductase activities and oxalate exudation in the nonmetallicolous populations may play an important role in increasing their efficiency in phytoremediation of As-contaminated soils.
  相似文献   

20.
[目的]研究黔西某煤矿区周边土壤重金属污染情况、重金属形态潜在风险及其周边重金属富集植物,为当地的重金属污染防治提供科学依据。[方法]采用潜在生态风险评价及模糊数学法的两种评价方法(单因素决定模型和加权平均模型)对煤矿区及非煤矿区土壤进行重金属生态风险评价,对影响土壤肥力的土壤理化指标进行检测,利用风险评估编码法对重金属形态进行分析,并采用生物富集系数法对煤矿区周边富集重金属植物进行筛选。[结果]煤矿区Hg,Cd,As,Zn,Cr及Ni平均值含量分别是背景值的2.47,3.65,2.00,1.23,1.74,1.69倍。煤矿区潜在生态危害趋势为:CdHgAsNiCrPbZn。模糊数学法单因素决定模型评价显示,非煤矿区污染大于煤矿区,加权平均模型则反之。煤矿区Cd,Cr,Cu,Mn,Ni,Pb及Zn潜在风险指数分别为69.17%,7.97%,8.24%,40.10%,45.29%,53.70%及29.90%。蜈蚣草对As富集系数大于1.00,火棘、构树、盐肤木、马桑、凤尾蕨及金丝梅等对Cd富集系数大于1.00,马桑及白蒿对Pb富集系数大于1.00。[结论]煤矿区存在重金属污染,以Cd,As,Hg较为严重。煤矿区周边土壤中重金属对环境构成的潜在风险顺序为:CdPbNiMnZnCuCr。对当地而言,蜈蚣草可作为煤矿区周边修复As污染的先行植物,凤尾蕨可作为修复Cd污染的先行植物,马桑可作为修复Pb污染的先行植物。  相似文献   

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