外源螯合剂柠檬酸和NTA对苎麻修复重金属Cd污染土壤的研究

发布时间：2018-06-10 18:53

本文选题：镉 + 苎麻　；参考：《湖南大学》2015年硕士论文

【摘要】：由采矿、冶金和电镀等工业生产、施肥和污水灌溉等农业活动以及大气沉降过程造成的重金属镉(Cd)污染问题在最近几年引起了广泛关注。由于Cd迁移能力强、生物毒性大、且不能被生物降解,易通过食物链在动植物和人体内富集,直接危害动植物和人类健康。因此,针对Cd污染土壤的生态修复和治理是人类可持续发展亟待解决的重要课题。污染土壤植物修复是一种通过在污染土壤上种植绿色植物来吸收、提取、隔离污染物经济、安全且环境友好的修复技术。螯合剂诱导植物修复技术主要是利用螯合剂的螯合能力活化污染土壤中的重金属,提高植物对该重金属的富集能力,促进植物体内重金属从地下部分向地上部分转移,从而提高植物对污染土壤的修复效率。苎麻是一种中国南方特有的麻类纤维作物,它生长迅速、生物量大、分布范围广、耐旱耐贫瘠、经济价值高、且对苎麻对Cd有较强的耐性,是一种较为理想的土壤Cd污染修复的目标植物,在水体和土壤Cd污染修复和尾矿废弃地的生态恢复中具有较高的研究价值和应用前景。本研究以苎麻为目标植物,以重金属Cd为目标污染物,采用天然可降解螯合剂NTA和柠檬酸为外源添加物,选择土壤盆栽实验,研究苎麻对重金属Cd的耐性和富集效应,以及NTA和柠檬酸对苎麻修复重金属Cd污染土壤的影响以及作用机理,以期为植物在重金属Cd污染土壤修复实践提供科学依据和理论基础。主要研究内容和结果如下:1采用土培方法,研究了在不同重金属Cd(0,5,10,25,50,100 mg/kg)浓度下苎麻(Bechmeria nivea(L.)Gaud)的富集能力及生理生化指标的变化规律。研究结果表明:在Cd胁迫下,随着Cd处理浓度的增加,苎麻的生物量、根际活力均呈先上升后下降的趋势;在Cd胁迫下,随着Cd处理浓度的增加,苎麻体内超过氧化物歧化酶(SOD),过氧化物酶(POD)活性和MDA含量随之显著增加,但是叶绿素含量和过氧化氢酶(CAT)活性下降;苎麻体内Cd的浓度和积累量随Cd处理浓度的增加逐渐增加,当处理Cd浓度到达100mg/kg,苎麻体内Cd的浓度和积累量分别为86.1mg/kg and 371.9 ug/株。苎麻的转移系数(TF)1且金属提取率(MER)≈0.1%,表明苎麻对重金属Cd的富集主要在根部,对Cd具有较强的稳定化能力。2研究螯合剂NTA和CA对苎麻修复Cd污染土壤的应用效果。研究了在两组Cd浓度(10mg/kg和50mg/kg)条件下,不同浓度的柠檬酸(CA)和氮三乙酸(NTA)(0,1,5,10 mmol/kg)对苎麻生物量、地上部分丙二醛(MDA)含量、叶绿素含量和抗氧化酶活性、苎麻各部分对Cd的积累的影响。结果表明,CA和NTA的应用均能促进苎麻的生长和提高Cd在苎麻体内积累。CA在促进苎麻生长、增强了苎麻对Cd的吸收方面效果显著,但是对提高Cd转移系数效果不明显;NTA对苎麻吸收和转移Cd有显著促进效果。苎麻体内CAT,SOD,POD活性和MDA含量变化表明CA和NTA缓解了Cd对苎麻的氧化胁迫。因此,外源螯合剂CA和NTA的应用有利于促进土壤Cd污染的植物修复。
[Abstract]:The heavy metal cadmium (Cd) pollution caused by the industrial production of mining, metallurgy and electroplating, fertilizer and sewage irrigation, and the heavy metal cadmium (Cd) pollution caused by the process of atmospheric sedimentation have attracted wide attention in recent years. Because of the strong migration ability of Cd, the biological toxicity is large and can not be biodegraded, and it is easy to concentrate by food chain in animals and plants and in human body, and it is directly endangered. Therefore, the ecological restoration and treatment of soil contaminated by Cd is an important issue to be solved for the sustainable development of human beings. The remediation of contaminated soil is a kind of remediation technology, which is induced by planting green plants on contaminated soil to absorb, extract and isolate pollutants economically, safely and environment-friendly. Chelating agent induction Phytoremediation technology mainly uses chelating ability to activate the heavy metals in the soil, improve the ability of plant to enrich the heavy metal, and promote the transfer of heavy metals from the underground part to the upper part of the plant, so as to improve the efficiency of the plant to repair the contaminated soil. It has rapid growth, large biomass, wide range of distribution, drought tolerance, barren, high economic value, and strong tolerance to Cd for ramie. It is an ideal target plant for remediation of soil Cd pollution. It has high research value and application prospect in the restoration of water and soil Cd pollution and ecological restoration of tailings wasteland. Taking ramie as the target plant, using heavy metal Cd as the target pollutant, the natural biodegradable chelating agent NTA and citric acid were used as exogenous additives. The soil pot experiment was used to study the tolerance and enrichment effect of Ramie on heavy metal Cd, as well as the effect of NTA and citric acid on the remediation of heavy metal Cd contaminated soil by ramie and the effect mechanism. The main research contents and results are as follows: 1 the enrichment ability and physiological and biochemical indexes of Ramie (Bechmeria nivea (L.) Gaud) under the concentration of different heavy metals Cd (0,5,10,25,50100 mg/kg) were studied by soil culture method. The results showed that in Cd, the results showed that in Cd, the results showed that in Cd Cd (L.) Gaud Under the stress, the biomass and Rhizosphere activity of ramie increased first and then decreased with the increase of Cd concentration. Under the stress of Cd, the activity of SOD, peroxidase (POD) and MDA in Ramie increased with the increase of Cd concentration, but the content of chlorophyll and the activity of catalase (CAT) in the ramie were increased. The concentration and accumulation of Cd in Ramie increased with the increase of Cd concentration. When Cd concentration reached 100mg/kg, the concentration and accumulation of Cd in ramie were 86.1mg/kg and 371.9 ug/ strain respectively. The transfer coefficient (TF) of Ramie (TF) 1 and metal extraction rate (MER) 0.1%, indicating that the enrichment of the heavy metal Cd in ramie is mainly in the root. .2 was used to study the effect of chelating agent NTA and CA on the application of chelating agent NTA and CA to the remediation of soil contaminated by ramie. In two groups of Cd concentrations (10mg/kg and 50mg/kg), different concentrations of citric acid (CA) and nitrogen three acetic acid (NTA) (0,1,5,10 mmol/kg) were applied to the biomass of ramie, the content of MDA (MDA), chlorophyll content and oxygen resistance in the aboveground part of the ramie The results showed that the application of CA and NTA can promote the growth of ramie and increase the accumulation of.CA in Ramie and increase the growth of ramie, and enhance the effect of Ramie on the absorption of Cd, but it has no obvious effect on Cd transfer coefficient, and NTA has a significant effect on the absorption and transfer of Cd in ramie, and NTA has a significant effect on the absorption and transfer of Cd in ramie. The results show that NTA has a significant effect on the absorption and transfer of Cd in ramie. The changes in CAT, SOD, POD activity and MDA content in Ramie showed that CA and NTA alleviated the oxidative stress of Cd to ramie. Therefore, the application of the exogenous chelating agent CA and NTA helped to promote the phytoremediation of soil Cd pollution.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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