115 resultados para Heavy metal pollution


Relevância:

80.00% 80.00%

Publicador:

Resumo:

超积累植物是植物提取修复的核心,同时也是污染环境修复领域研究的热点与前沿。针对目前已发现的超积累植物数量与对重金属提取种类较少的现状,并根据修复实践的需求,本研究确立了以超积累植物的筛选为主要研究内容并就一些强化措施进行了初步探索,同时根据已报道的植物修复研究的阶段性成果,对污染土壤植物修复的基本概念、原理、方式、强化机制等相关的修复过程进行了系统总结,结果如下:(1)超积累植物应同时具有四个基本特征,即临界含量特征、转移特征、耐性特征和富集系数特征。(2)龙葵和球果掉菜是Cd超积累植物,在Cd投加浓度为259/kg条件下,其茎和叶中Cd含量分别为103.80mg/kg和124.57mg/kg及107.7Omg/kg和150.10mg/kg。植物体内积累的Cd主要分布在茎和叶中。这2种植物不具有同时超积累Pb、Cu或Zn的能力。(3)施加鸡粪后植物对Cd的提取率提高了35.7%~97.0%;采用开花期收获超积累植物的复种方式,植物提取率可以提高到1.43倍和1.75倍。(4)以杂草为筛选对象,将成为筛选超积累植物的一个突破口。(5)盆栽筛选试验具有可操作性强、易于实施等优点,是筛选超积累植物值得尝试的一种方法。(6)现发现的超积累植物几乎均来源于污染区,本研究表明,未污染区也可能存在超积累植物。(7)栽培措施对植物修复效果有较大影响,与现代农业高新技术相结合是植物修复技术成功应用于修复实践的一条捷径。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

绞股蓝(Gynostemma pentaphyllum)系葫芦科绞股蓝属植物,药用价值广泛,但其野生资源日趋减少,绞股蓝主要药效成分为绞股 蓝皂甙。利用组织和细胞培养生产绞股蓝皂甙是合理开发利用和保护绞股蓝资源的可能途径之一。本文对绞股蓝组织培养中培养基 的蔗糖和激素的组成以及各种胁迫条件:渗透压、重金属离子、真菌诱导物等对皂苷产量的影响进行了初步研究。其中,渗透压、 重金属离子、真菌诱导物对绞股蓝愈伤组织皂甙产量的影响尚未见报道。1. 蔗糖对绞股蓝愈伤组织之生长影响显著,2,4-D对绞股 蓝愈伤组织皂甙含量、产量影响显著。增加蔗糖用量,减少2,4-D的用量可提高皂甙产量。2. Mn++ 用量的提高抑制绞股蓝愈伤组 织的生长,但可促进皂甙含量、产量的提高。Mn++用量提高至MS培养基的20-30倍时可使皂甙产量增加近一倍,而提高Cu++浓度的 作用不明显。3. 甘露醇用量增加抑制绞股蓝愈伤组织的生长,但可使皂甙含量、产量提高。0.680mol·l-1甘露醇可使皂甙产量提 高83%,而Nacl较大抑制愈伤组织的生长并使皂甙产量降低。4. 米曲霉粗提物对绞股蓝愈伤组织生长先略微促进,然后抑制,而根 霉粗提物则使愈伤组织生长受抑制;两者对皂甙含量、产量的作用相似:在较低浓度范围内升高,然后下降。米曲霉粗提物可提高 产量一倍,根霉粗提物可提高42%。这些结果为高产细胞系的筛选和生长、生产培养条件的优化积累了资料。在综述部分,对植物 细胞培养中组织和器官分化、细胞结构变化、生化水平的变化与次生物合成和积累的关系作了讨论。Gynostemma pentaphyllum blongs to Gynostemma, Cucurbitaccae. It has a wide medical use, but its wild resource is threatened by people's excessive use. Its effective medical components are gypenosides. For reasonable use and protect its resource, it is a possible way to product gypenosides by plant tissue and cell culture. This paper has a primary study on the components of sucrose and hormones and a variety of stress conditions: osmostic pressure, heavy metal ion, fungal elicitors in the medium for the calli culture. The effects of osmostic pressure, heavy metal ion and fungal elicitors on the calli of Gynostemma pentaphyllum have not been reported. 1. Sucrose had a significant effect on the growth of the calli, 2,4 D had notable effects on the gypenosides content and production of the calli. Increased the concentration of sucrose and decreased the concentration of 2,4 D improved the production of gypenosides. 2. Increased the concentration of Mn++ inhibited the growth of the calli, but improved the content and production of gypenosides. The optimum concentration was 20-30 times as MS medium which improved the production 100%. Increased the concentration of Cu++ had not a notable effect. 3. Increased the concentration of mannitol inhibited the growth of the calli, but improved the content and production of gypenosides. The optimum concentration was 0.680mol·l-1 which improved the production 83%. Nacl apparently inhibited the growth of the calli and decreased the production of gypenosides. 4. The crude preparation of Aspergillus oryzae inhibited the growth of the calli that in low concentration. The crude praparation of Rhizopus formosensis inhibited the growth of the calli throughout. Their effects on the content and production of gypenosides are alike, but the former is higher than the latter. On the optimum concentration, each crude preparation improved the production 100% (Aspergillus oryzae), 42%(Rhizopus formosensis). These results has accumulated some informantion on the select of high yield cell strains and choose the best culture conditons for the growth and gypenosides product of the calli. In the review, it is discussed that the differentiation on tissue-organal, cellular and biochemical levels related to the synthesis and accumulation of secondary metabolites in plant culuture.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

本研究应用微波消解ICP-AES 法对62 个小麦品种及3 个地区土壤的锌铁硒含量进行了分析测定,发现不同小麦品种中微量元素含量差异很大,姊妹系间也存在差异。含铁量最高与最低的小麦品种铁含量相差29.68mg/kg。含锌量最高与最低的小麦品种锌含量相差46.70 mg/kg。含硒量最高与最低的小麦品种硒含量相差0.056 mg/kg。对不同地点的小麦及土壤中锌铁硒含量进行方差分析,发现双流和西昌两地种植小麦的铁含量和硒含量均有显著差异,西昌和荣县种植的锌含量有显著差异。在3 个地点中双流种植小麦硒含量最高,西昌种植小麦的铁和锌含量最高。 通过对小麦微量元素含量与土壤中微量元素含量进行了相关性分析,结果表明:小麦中的锌铁含量与土壤中的锌铁含量呈显著正相关,土壤中铁与锌含量呈极显著正相关,小麦中铁与锌含量也呈极显著正相关。随着土壤微量元素锌铁的提高,小麦中的锌铁元素含量同时提高,而且小麦对两种元素的吸收互相促进。土壤中的硒含量与锌铁含量呈负相关。小麦中硒含量也与锌铁含量也呈负相关。说明锌和铁与硒互相拮抗。小麦硒含量与土壤硒含量呈正相关,但不显著。表明土壤硒含量可以影响小麦硒含量,但不是决定因素,小麦硒含量与小麦自身因素有关。 对姊妹系G290(高硒含量)和G289(低硒含量)进行抗重金属胁迫和抗旱性实验发现,高硒品种G290的抗逆性优于低硒品种G289。 利用RAPD 技术对7 个姊妹系进行遗传差异分析发现,高硒材料G290出现了特异条带,分别标为1、2、3、4,其他姊妹系品种中未发现特异条带,回收4 条特异条带并连接转化,得到目的片段1、2、3 的重组子,进行测序。NCBI 中结果显示没有找到植物中的同源序列,说明特异序列可能是未发现的基因片段,推测可能与小麦硒含量有关,有待进一步研究。 以上研究结果,对小麦营养研究及功能性小麦的筛选和栽培具有指导作用。 In this study, we determinated the contents of zinc, iron, selenium in 62 wheat cultivars and soil samples of three regions by method of microwave digestion/ ICPAES,found that there was great difference of zinc, iron, selenium contents in different wheat cultivars as well as different sister lines. Iron content difference was 29.68 mg/kg between the highest-iron-content cultivar and the lowest one, and zinc content difference was 46.70 mg/kg , selenium content difference was 0.056 mg/kg. Anova analysis was made on contents of zinc, iron, selenium in wheat and soil samples of different locations, significant differences of Fe and Se contents were found between wheat in Shuangliu and Xichang, significant difference of Zn content was found between wheat in Xichang and Rongxian. Se content in wheat of Shuangliu was highest, Fe and Zn contents in wheat of Xichang were highest. Relativity analysis was made on three trace elements in Wheat and in soil, the result showed that there was significant positive correlation of zinc, iron content between in Wheat and in soil, as well as between Fe and Zn both in wheat and in soil. With the improving of Zn, Fe contents in soil, contents of Zn and Fe in wheat increased and absorption of Zn and Fe in wheat will mutual promote. Negative correlation of Se and Zn contents was found in wheat and soil, but not significant, that meant the antagonism of Se and Zn. Positive correlation of Se content in wheat and soil was found. High selenium content G290 and low selenium content G289 in sister lines were selected for heavy metal stress and drought resistance experiments, the result showed that the resistance of high-selenium-content cultivar was better than low selenium one. Analysis on genetic difference was made by RAPD, and specific bands were selected, marked 1,2,3,4, no more specific bands were found in other sister lines.4 bands were recovered, ligated to T-vector and transformed E.coli. Three recombinant plasmids were obtained and sequenced. NCBI Blast showed there was no homology with other plants. It implied that these fragments probably be new genes and maybe were related to selenium in wheat. It needs further research. This paper would be useful for the study of wheat nutrition as well as selection and cultivation of functional wheat.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Electron Cyclotron Resonance (ECR) ion source is regarded as the most efficient machine to produce stable multiple charge state ion beams. Because of the special characteristics, all-permanent magnet ECR ion sources have been widely adopted around the world to produce stable ion beams of multiple charge state with good repetition have been widely adopted around the world to produce stable ion beams of multiple charge state with good repetition and high duty factor for compact research platforms and ion beam implanters. In this paper, all-permanent magnet ECR ion sources developed at IMP are presented, and typical parameters and performances are discussed. The high charge state source, LAPECR2, is mainly used to produce intense high charge state ion beams, and the LAPECR1 source is designed to produce intense ion beams of medium and low charge state. An improved LAPECR1-M is specially designed to produce heavy metal ion beams of low charge state. These ECR ion sources have been adopted by different experimental terminals at IMP and, with their nice performance, many experimental studies could be possible. 中文文摘:ECR(电子回旋共振)离子源是产生稳定的强流多电荷态离子束流最有效装置。全永磁ECR 离子源因其独特的特点为很多中小型多电荷态离子束流实验平台与离子注入机等系统所采用,为后者产生重复性好、稳定性强的多电荷态离子束流。本文着重论述了中国科学院近代物理研究所研制的几台全永磁多电荷态ECR 离子源及其特性与典型性能,如能产生强流高电荷态离子束流的高性能全永磁离子源LAPECR2,能产生强流中 低电荷态离子束流的LAPECR1,能产生多电荷态重金属离子束流的LAPECR1-M 等。这些性能稳定的离子源为提高近代物理研究所相关试验平台的性能提供了关键的束流品质保障。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Superconducting electron cyclotron resonance ion source with advanced design in Lanzhou (SECRAL) is an all-superconducting-magnet electron cyclotron resonance ion source (ECRIS) for the production of intense highly charged ion beams to meet the requirements of the Heavy Ion Research Facility in Lanzhou (HIRFL). To further enhance the performance of SECRAL, an aluminum chamber has been installed inside a 1.5 mm thick Ta liner used for the reduction of x-ray irradiation at the high voltage insulator. With double-frequency (18+14.5 GHz) heating and at maximum total microwave power of 2.0 kW, SECRAL has successfully produced quite a few very highly charged Xe ion beams, such as 10 e mu A of Xe37+, 1 e mu A of Xe43+, and 0.16 e mu A of Ne-like Xe44+. To further explore the capability of the SECRAL in the production of highly charged heavy metal ion beams, a first test run on bismuth has been carried out recently. The main goal is to produce an intense Bi31+ beam for HIRFL accelerator and to have a feel how well the SECRAL can do in the production of very highly charged Bi beams. During the test, though at microwave power less than 3 kW, more than 150 e mu A of Bi31+, 22 e mu A of Bi41+, and 1.5 e mu A of Bi50+ have been produced. All of these results have again demonstrated the great capability of the SECRAL source. This article will present the detailed results and brief discussions to the production of highly charged ion beams with SECRAL.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

本项工作利用多种分析手段(FTIR、TDS、RBS/C、AFM、SEM),对100keV He离子不同剂量(0.5,2.0,8.0×1016cm-2)注入的尖晶石中缺陷的形成及其对重金属原子的俘获效应进行了研究。在FTIR谱上观察到了Al-O键的共振吸收峰随剂量增加向小波数方向移动和随退火温度升高向大波数方向回复;随退火温度增加这三组样品的晶格损伤均经历先增大后减小的过程,但随剂量不同晶格损伤开始增加的温度不同;注入剂量为2.0×1016 cm-2样品在退火过程中其表面发生了形变,随剂量增加样品表面发现起皮现象。上述差异被认为是样品中不同缺陷的形成所引起的。随后,尝试了利用He离子注入形成的空位型缺陷俘获重金属原子的方法在尖晶石中合成金属纳米颗粒。吸收光谱上SPR吸收峰的出现,证实了金属纳米颗粒的形成

Relevância:

80.00% 80.00%

Publicador:

Resumo:

A plasticized Cr3+ ion sensor by incorporating 2,3,8,9-tetraphenyl-1,4,7,10-tetraazacyclododeca-1,3,7,9-tetraene (TTCT) ionophore exhibits a good potentiometric response for Cr3+ over a wide concentration range (1.0×10-6-1.0×10-1 M) with a slope of 19.5 mV per decade. The sensor response is stable for at least three months. Good selectivity for Cr3+ in comparison with alkali, alkaline earth, transition and heavy metal ions, and minimal interference are caused by Li+, Na+, K+, Co2+, Hg2+, Ca2+, Pb2+ and Zn2+ ions, which are known to interfere with other chromium membrane sensors. The TTCT-based electrode shows a fast response time (15 s), and can be used in aqueous solutions of pH 3 - 5.5. The proposed sensor was used for the potentiometric titration of Cr3+ with EDTA and for a direct potentiometric determination of Cr3+ content in environmental samples.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The chelates formed between the heavy metal ion Pb(II) and the reagents 8-hydroxy-5-quinolinesulphonic acid, 8-hydroxy-7-quinolinesulphonic acid and 8-hydroxy-7-iodo-5-quinolinesulphonic acid exhibit strong room temperature phosphorescence (RTP) if retained on the surface of anion exchange resin beads. Based on the on-line formation, in a flow-injection system, of such RTP lead chelates and their transient immobilization on an anion exchange resin, three flow-through optosensing systems are investigated for lead in sea water. Optimum experimental conditions and the analytical performance characteristics of the three optosensors are discussed. Relative standard deviations (RSDs) of the order of 3% are typical at 100 ng ml−1 Pb(II) and the active sensing phases can easily be regenerated by passing 500 μl of 6 M hydrochloric acid. A lead(II) detection limit of 0.1 ng ml−1 (3×background SD, for 2 ml sample injection volumes) was achieved for the optosensor based on 8-hydroxy-7-quinolinesulphonic acid. Possible interferences present in sea water, including cations and anions which could affect the sensor response, are discussed in detail. Finally, the selected RTP flow-through optical sensor has been successfully tested for the determination of lead in sea water at a few ng ml−1.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This article reports on the performance of a bismuth-coated carbon microdisk electrode (BiFμE) for the determination of trace heavy metals by anodic stripping voltammetry (ASV). The BiFμE was prepared by electrodeposition of a metallic bismuth film onto the microdisk, by applying an in-situ electroplating procedure. To test the performance of the BiFμE, ASV measurements were performed on synthetic solutions containing Cd2+, Pb2+, and Cu2+ as target ions. The results indicated that cadmium and lead gave well-defined ASV peaks with no interference, and their quantitative determination could be carried out straightforwardly. In particular, linear calibration curves over the range 5.0 x 10-8-1.0 x 10-6M for both ions, and detection limits of 7.8 and 2.9 nM, for cadmium and lead, respectively, after applying a 60 sec preconcentration step, were obtained. The reproducibility was also satisfactory, the relative standard deviation (RSD) being within 2.5% for both ions. Copper, instead, gave an ASV response that. in most experimental conditions, overlapped with that of bismuth. This circumstance made the determination of copper at the BiFμE difficult. Since the latter element could be detected reliably at the uncoated carbon microdisk electrode (CμE), both BiFμE and CμE were employed, respectively, for the determination of lead and copper ions in drinking water, wine, and tomato sauce.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

以黄土高原沟壑区的苹果园为研究对象,对6~36 a苹果园土壤重金属含量状况进行研究,结果发现,该区苹果园的高投入种植管理模式,能够影响重金属在土壤中的迁移与富集,使土壤重金属含量发生明显变化。土壤Cu含量随树龄增加而增加,20 a以上的土壤-果树系统对土壤Cu的输入与输出趋于平衡,Cu含量变化不大,且耕层土壤Cu含量较高。Cr含量随树龄线性递增,36 a果园0~20 cm,20~40 cm和40~60 cm土层Cr含量分别比6 a果园增加27.14%,17.09%和19.17%。Cd含量随树龄增加先增加后减少,长期大量施用磷肥是土壤Cd的主要来源,果园生态系统深层土壤Cd含量的峰值比耕层提前出现。Pb含量以15~26 a果园含量最高,树龄<15 a和>26 a时Pb含量较低。Hg含量则以15 a为转折点,在不同土层上呈现出不同的变化趋势。As含量在树龄<15 a时逐渐降低,15~20 a时逐渐增加,20 a以后果园土壤As含量趋于不变,且各土层之间差异不显著。

Relevância:

80.00% 80.00%

Publicador:

Resumo:

In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+. The experimental data have been analyzed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results showed that the biosorption equilibrium was well described by both the Langmuir and Redlich-Peterson isotherms.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Electrochemical measurement of respiratory chain activity is a rapid and reliable screening for the toxicity on microorganisms. Here, we investigated in-vitro effects of toxin on Escherichia coli (E. coli) that was taken as a model microorganism incubated with ferricyanide. The current signal of ferrocyanide effectively amplified by ultramicroelectrode array (UMEA), which was proven to be directly related to the toxicity. Accordingly, a direct toxicity assessment (DTA) based on chronoamperometry was proposed to detect the effect of toxic chemicals on microorganisms. The electrochemical responses to 3,5-dichlorophenol (DCP) under the incubation times revealed that the toxicity reached a stable level at 60 min, and its 50% inhibiting concentration (IC50) was estimated to be 8.0 mg L-1. At 60 min incubation, the IC50 values for KCN and As2O3 in water samples were 4.9 mg L-1 and 18.3 mg L-1, respectively. But the heavy metal ions, such as Cu2+ Pb2+ and Ni2+, showed no obvious toxicity on E. coli.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

This work herein reports the approach for the simultaneous determination of heavy metal ions including cadmium (Cd(II)), lead (Pb(II)), and chromium (Cr(VI)) using a bismuth film electrode (BFE) by anodic stripping voltammertry (ASV). The BFE used was plated in situ. Due to the reduction of Cr(VI) with H2O2 in the acid medium, on one hand, the Cr(III) was produced and Cr(VI) was indirectly detected by monitoring the content of Cr(III) using square-wave ASV. On the other hand, Pb(II) was also released from the complex between Pb(II) and Cr(VI). Furthermore, the coexistence of the Cd(II) was also simultaneously detected with Pb(II) and Cr(VI) in this system as a result of the formation of an alloy with Bi. The detection limits of this method were 1.39 ppb for Cd(II), 2.47 ppb for Pb(II) and 5.27 ppb for Cr(VI) with a preconcentration time of 120 s under optimal conditions (S/N = 3), respectively. Furthermore, the sensitivity of this method can be improved by controlling the deposition time or by using a cation-exchange polymer (such as Nafion) modified electrode.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Ordered N-methylimidazolium functionalized mesoporous silica (SBA-15) anion exchangers were directly synthesized by co-condensation of tetraethoxysilane with 1-methyl-3(triethoxysilylpropyl)imidazolium chloride. The prepared samples with rod-like morphology showed high surface areas (> 400 m(2) g(-1)), well-ordered pores (> 58 angstrom), and excellent thermal stability up to 387 degrees C. The adsorption behaviors of Cr(VI) from aqueous solution on the anion exchangers were studied using the batch method. The anion exchangers had high adsorption capacity ranging from 50.8 to 90.5 mg g(-1), over a wider pH range (1-8) than amino functionalized mesoporous silica. The adsorption rate was fast, and the maximum adsorption was obtained at pH 4.6. The adsorption data for the anion exchangers were consistent with the Langmuir isotherm equation. Most active sites of the anion exchangers were easily accessible. The mixed solution of 0.1 mol L-1 NH3 center dot H2O and 0.5 mol L-1 NH4Cl was effective desorption solution, and 95% of Cr(VI) could be desorbed.