植物修复技术中有关土壤重金属活化机制的研究进展

植物修复技术是现在环境污染研究领域的一个热点问题,而植物提取是植物修复技术一个重要分支。本文主要从三个方面综述了植物提取中土壤重金属活化的机制问题。1.植物本身分泌特殊物质来螯合溶解难溶性金属;2.通过某些微生物或微生物和植物的共生体促进植物对重金属的吸收;3.通过一些土壤改良措施如螯合剂、酸性肥料等的施用增加重金属的有效性,从而提高植物对重金属的提取效率。土壤重金属的植物修复涉及到的学科很多,在进行研究时应加强学科之间的协作研究。     

过量硼对植物的毒害及高硼土壤植物修复研究进展

硼作为一种植物必需元素,在土壤中过量存在会对植物产生毒害,硼对植物的毒害作用以及利用植物修复高硼土壤已经日益受到关注。目前,硼对不同类型植物的毒害特点,植物的耐受机制还不十分清楚。特别是对于硼污染的植物修复,其研究还处于起步阶段。本文分别从植物的表观症状、生理生化和基因水平等层次,综述了过量硼对植物的毒害,并从高耐受性、超富集能力植物筛选,以及转基因技术应用等角度回顾了硼污染的植物修复研究进展。在此基础上,提出了当前相关研究存在的主要问题,并对未来的研究进行了展望。     

重金属污染土壤的植物强化修复研究进展

随着工农业生产的快速发展,土壤重金属污染日益严重,土壤重金属污染的高效快速修复技术备受关注。在各种土壤重金属污染修复技术中,植物修复技术因其清洁、简单、高效、低消耗等优点,得到人们的认可,具有良好的发展前景。论文综述了土壤重金属污染来源及现状,植物修复技术的基本原理及特点,植物强化修复技术的研究进展,分析了当前植物强化修复技术中存在的问题,并指明了植物强化修复技术的发展方向,以期为土壤重金属污染的快速、绿色修复提供理论依据。     

香薷植物修复铜污染土壤的研究进展

土壤铜污染有自然来源和人为来源。铜污染土壤中有机质、Fe／Al氧化物对铜的专性吸附，是影响土壤中铜生物有效性的主要因素。近年来，我国原生植物修复材料如海州香薷、鸭跖草、酸模、紫花香薷在国内铜污染土壤的研究中得到广泛应用。其中．采用海州香薷开展铜污染土壤植物修复机理和修复技术的研究，已从实验室水培、盆栽试验的生长反应特性、耐及解铜毒的生理生化反应，进展到室外大田修复的示范工程及技术推广阶段。紫花香薷在重金属复合污染土壤上，也有修复前景。开展植物修复材料的产后处置研究，综合利用和深加工，增大植物修复材料价值，对加强植物修复工程的示范和推广步伐，有重要意义。     

螯合剂强化棉花对镉污染土壤修复的初步研究

采用土壤盆栽试验研究了4种有机螯合剂柠檬酸(CA)、乙二胺四乙酸(EDTA)、乙二醇双四乙酸(EGTA)和乙二胺二琥珀酸(EDDS)在不同添加量(0,2.5,5,7.5mmol/kg)时对棉花修复镉(Cd)污染土壤的影响。结果表明,添加螯合剂显著提高了土壤水溶态Cd的含量,添加EDTA、EGTA、EDDS 3种螯合剂,使水溶态Cd含量分别提高了46.5~92.2,52.0~101.1,16.7~84.1倍,其中EGTA增加的幅度最大。棉花生长受有机螯合剂种类和添加量的影响,EDDS和EDTA在高添加量(7.5mmol/kg)时对棉花产生较大的毒害作用,但在培养期内添加螯合剂对植株生物量无显著影响。使用螯合剂显著促进棉花植株Cd含量和地上部分的积累量,其中以EGTA处理效果最佳,地上部Cd含量为对照(CK)的4.01~5.20倍。从地上部Cd积累量和转运系数来看,4种螯合剂EGTA效果最好,CA效果最差。依据研究结果,棉花可作为土壤Cd污染修复植物使用,在植株收获前7d左右添加EGTA螯合剂可有效提高棉花对Cd污染土壤的修复效率。     

Relationship Between Extractable Metals in Acid Soils and Metals Taken Up by Tea Plants

Abstract

The accumulation of heavy metals in plants is related to concentrations andchemical fractions of the metals in soils. Understanding chemical fractions and availabilities of the metals in soils is necessary for management of the soils. In this study, the concentrations of copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn) in tea leaves were compared with the total and extractable contents of these heavy metals in 32 surface soil samples collected from different tea plantations in Zhejiang province, China. The five chemical fractions (exchangeable, carbonate‐bound, organic matter‐bound, oxides‐bound, and residual forms) of the metals in the soils were characterized. Five different extraction methods were also used to extract soil labile metals. Total heavy metal contents of the soils ranged from 17.0 to 84.0 mgCukg^?1, 0.03 to 1.09 mg Cd kg^?1, 3.43 to 31.2 mg Pb kg^?1, and 31.0 to 132.0 mg Zn kg^?1. The concentrations of exchangeable and carbonate‐bound fractions of the metals depended mainly on the pH, and those of organic matter‐bound, oxides‐bound, and residual forms of the metals were clearly controlled by their total concentrations in the soils. Extractable fractions may be preferable to total metal content as a predictor of bioconcentrations of the metals in both old and mature tea leaves. The metals in the tea leaves appeared to be mostly from the exchangeable fractions. The amount of available metals extracted by 0.01 mol L^?1 CaCl₂, NH₄OAc, and DTPA‐TEA is appropriate extractants for the prediction of metals uptake into tea plants. The results indicate that long‐term plantation of tea can cause sol acidification and elevated concentrations of bioavailable heavy metals in the soil and, hence, aggravate the risk of heavy metals to tea plants.     

蚯蚓在植物修复重金属污染土壤中的应用前景

重金属污染土壤的植物修复技术是绿色生物技术,该技术的应用受制于两个主要因素:超积累植物生物量小和土壤中重金属有效性低。本文在收集大量资料基础上,论述了蚯蚓与重金属的相互关系:重金属对蚯蚓的毒理效应和蚯蚓对重金属的忍耐力。根据在重金属污染土壤中,蚯蚓活动能提高植物生物量和土壤中的重金属的生物有效性,论证了在重金属污染土壤植物修复技术中引入蚯蚓的可行性,并指出引入蚯蚓的植物修复技术当前的研究热点及今后的研究方向。     

Phytoremediation Possibilities of Boron-Contaminated Environments by Wild Plants Growing on Boron Reserve Areas in Turkey

Turkey has almost 70% of the total boron (B) in the world, and B-reserve areas form a special habitat in terms of plant–environment relationships. In this study, these relationships were used to investigate phytoremediation possibilities for B-contaminated environments. Field studies were carried out in seven different open B mine sites and their environments in four different provinces of Turkey. At the end of chemical analyses of soil and plant samples, 11 wild and potential phytoremediator plant species were determined; two of them were aquatic whereas nine were terrestrial. Some of the species were halophytes. Puccinella distans subsp. distans (Poaceae) and Gypsophila perfoliata subsp. perfoliata (Caryophyllaceae) showed both the greatest tolerance and greatest B accumulation ratios. The results of the present study could be used as a tool to improve effective and environmentally friendly management strategies for both aquatic and terrestrial environments contaminated with high B concentrations.     

Indigenous Plant Species with the Potential for the Phytoremediation of Arsenic and Metals Contaminated Soil

Here we present results of a survey conducted to identify and characterize spontaneously growing arsenic-tolerant plant species of the area around the old arsenic/gold mine in ZlotyStok (Poland), with respect of their potential use in phytoremediation. Plants and soil from their rhizosphere were sampled and analyzed for concentrations of As and accompanying Mn, Fe, Mg, Ca, Al, Cu, Zn, Ba, Pb, Ni, Cs, V, Cr, Sr, Rb, Bi, Mo and U. The soil contained primarily very high As, Pb and Al concentrations (up to 7,451, 1,058 and 31,272 mg/kg respectively). The ability of identified species to modify the amount of bioavailable arsenic in their rhizosphere was determined by single extractions of soil samples with the use of water, phosphate buffer, EDTA, and acetic acid. Although As-hyperaccumulators were not found, Calamagrostis arundinaca was identified as a new species which successfully carried out the natural phytoextraction of arsenic. This plant was able to increase substantially the arsenic availability in the soil, and likely due to efficient uptake decreased the total As concentration within the root zone by around 40% relative to the reference soil. Thus, it has high potential for phytoremediation. The lowest amount of available arsenic was found in the rhizosphere of Stachys sylvatica, the species with the lowest As shoot concentration (compared with other plant species). It was proposed as a good candidate for phytostabilization.     

Trace Metals in Soil and Plants Subjected to Strong Chemical Pollution

The total concentrations of ten elements (Ag, As, Co, Cs, Fe, Ir, Ni, Rb, Sb, and Sc) were determined in soil and vegetation samples from the surroundings of a Cu-Ni smelter in Monchegorsk, Northwest Russia, and a background area in Naruska, North Finland. The samples were analysed by epithermal neutron activation analysis (ENAA). Elements emitted from the smelter (Ag, As, Co, Ir, Ni, and Sb) were mostly accumulated in the topsoil. Some elements also appeared to contaminate deeper soil layers. In both soil and vegetation the metal concentrations decreased with increasing distance from the smelter. The most significant contributor to the high concentrations of Fe and Sc near the smelter was probably damaged ground vegetation and subsequent wind erosion. Possibly high geochemical abundance of Fe and Sc may also have been a contributing factor. Concentrations of Cs and Rb in soil and vegetation generally increased with increasing distance from the pollution source. High negative correlations were evident between these elements and the elements emitted from the smelter, suggesting that cation exchange of Cs and Rb by the elements supplied from the smelter was likely occurring in the surface soil.     

不同来源蜈蚣草吸收富集砷的特征及植物修复效率的探讨

蜈蚣草是一种As的超富集植物,在As污染土壤的植物修复上具有极大的潜力.对中国南方广泛分布的蜈蚣草及其生长的土壤的As含量、形态及土壤理化性质的调查分析表明,蜈蚣草生长的土壤As含量范围为33.7～1396 mg/kg,相应地,蜈蚣草地上部As含量范围为48.5～1104 mg/kg.除阳离子交换量(CEC)外,不同采样地区蜈蚣草生长土壤的理化性质指标,包括pH、总有机质(TOM)和质地均存在显著性差异,反映野外蜈蚣草可生长在不同性质的土壤上.基于回归分析的预测模型显示,蜈蚣草对As污染土壤的植物修复效率随土壤As含量的增加而逐渐降低,蜈蚣草较适用于轻度As污染土壤的修复,对于高As污染土壤,需结合其他修复措施.     

硒缓解植物重金属胁迫和累积的机制

硒(Se)在提高植物抗逆性、缓解重金属胁迫以及降低植物对重金属吸收方面有着重要的作用。本文综述了Se参与缓解植物重金属胁迫和累积的机制,Se能够缓解重金属的胁迫,主要是因为在植物体内由Se转化而来的相关产物的生理生化作用产生的综合效果。Se是谷胱甘肽过氧化物酶(GSH-Px)的必需组分,GSH-Px利用谷胱甘肽(GSH)将有毒的过氧化物还原成无毒的物质,清除由重金属引起的自由基。Se可以激活植物螯合肽(PC)合成酶及增加PC合成的前体,使植物产生更多的PC,形成更多的重金属-PC配合物。Se还可以与重金属形成大分子的复合物,降低重金属的毒害。Se能够与多种重金属元素产生拮抗效应,降低植物对重金属的吸收。     

火电厂烟气脱硫石膏重金属含量监测与分析

为有效利用脱硫石膏改良盐碱地,避免改良过程中带来土壤重金属污染风险,在山西省境内不同地区选择有代表性的8个火电厂烟气脱硫废弃物-脱硫石膏采样点,在1a内每月定期进行脱硫石膏的采集及重金属(Cd、Ni、Pb、Cu、Zn、Cr、Hg、As)浓度的分析。结果表明,8个采样点脱硫石膏中重金属Cd、Ni、Pb、Cu、Zn、Cr、As含量基本低于适用于耕地的国家土壤环境质量二级标准(GB 15618-1995),而1~8号采样点只有一小部分脱硫石膏中Hg含量低于适用于耕地的国家土壤环境质量二级标准(GB 15618-1995)。8号采样点除极个别批次重金属含量较1~7号采样点低之外,其余均高于1~7号采样点脱硫石膏中重金属浓度。因此,在利用脱硫石膏改良盐碱地之前,要明确脱硫石膏中不同重金属元素浓度,适量施用脱硫石膏,达到改良盐碱地,保证农产品安全,提高作物产量的目的。     

Phytodiversity for Metals in Plants Grown in Urban Agricultural Lands Irrigated with Untreated City Effluent

In developing countries, farmers use effluent as a source of irrigation and nutrients and the government takes this practice as a viable option for disposal. Sewage samples have hazardous electrical conductivities (EC), sodium adsorption ratios (SARs), and residual sodium carbonate (RSC) for irrigation, but metals were close to upper permissible limits. The EC of saturated soil paste extract (EC_e) ranged from 2.18 to 4.02 dS m^–1 and soil SAR 7.72 to 16.00 in soils 0.2 m deep. Average cadmium (Cd), nickel (Ni), lead (Pb), zinc (Zn), and copper (Cu) in soils ranged from 0.02 to 0.13, 0.00 to 4.45, 2.27 to 4.57, 0.71 to 13.76, and 3.17 to 10.37 mg kg^–1, respectively. Plants acquired metal contents greater than in raw sewage or soils. The wide biodiversity regarding metals in shoots of natural and planted vegetation that receives raw sewage is of practical significance. It seems imperative to study under controlled conditions various plants' metal tolerance and mechanisms of metal partitioning among plant parts.     

Interactions between Essential Nutrients with Platinum Group Metals in Submerged Aquatic and Emergent Plants

Increasing environmental concentrations of platinum group metals (PGMs), in particular platinum (Pt), rhodium (Rh) and palladium (Pd), from catalytic converters has been reported worldwide. The impact of these three metals on the uptake and use of essential mineral nutrients was examined using two plant models: the submerged aquatic plant, Elodea canadensis, and the terrestrial emergent plant, Peltandra virginica. Plants were grown for 2 weeks in nutrient solutions with either Pt⁴⁺ at concentrations between 0.05 and 5 mg/L, or a 0.1 mg/L Pt⁴⁺, Rh³⁺, Pd²⁺ mixture. Some treatments received additional Ca²⁺, Zn²⁺, or humic acid (with varying pH) to study how these conditions affected PGM uptake. Metal concentration analyses were conducted using a graphite furnace atomic absorption spectrometer (GFAAS) or an inductively coupled plasma emission spectrometer (ICP). Growth response was assessed through total chlorophyll content. There was significant Pt accumulation in plant tissues, from 55 to 326 times the concentration in nutrient solution. At pH 8, the addition of humic acid doubled Pt accumulation in comparison to the control. Additional exogenous minerals did not significantly affect PGM uptake, nor did the uptake of PGMs interfere with the uptake of Ca, Fe or Cu. Synthesis of chlorophyll in new shoots was not affected by Pt accumulation; however, visible chlorosis was observed in older shoots at 5 ppm Pt. Roadside Daucus carota samples from four heavy traffic locations in Dutchess County (New York) were also assessed for PGM content. Pt, Pd and Rh concentrations averaged 14.6, 10.2, and 0.7 μg/g, respectively.     

Phytoremediation Potentials of Sunflowers (Tithonia diversifolia and Helianthus annuus) for Metals in Soils Contaminated with Zinc and Lead Nitrates

Two species of sunflower, i.e., Tithonia diversifolia and Helianthus annuus, were investigated for their potential to remove heavy metals from contaminated soils. Dried and mature T. diversifolia (Mexican flower) seeds were collected along roadsides, while H. annuus (sunflower) seeds were sourced from the Department of PBST, University of Agriculture Abeokuta, Nigeria. The contaminants were added as lead nitrate (Pb (NO₃)₂) and zinc nitrate (Zn (NO₃)₂) at 400 mg/kg which represents upper critical soil concentration for both Pb and Zn. The results indicated that T. diversifolia mopped up substantial concentrations of Pb in the above-ground biomass compared to concentrations in the roots. The concentrations in the leaf compartment were 87.3, 71.3, and 71.5 mg/kg at 4, 6, and 8 weeks after planting (AP), respectively. In roots, it was 99.4 mg/kg, 97.4 mg/g, and 77.7 mg/kg while 79.3, 77.8, and 60.7 mg/kg were observed in the stems at 4, 6, and 8 weeks AP, respectively. Observations with H. annuus followed the pattern found with T. diversifolia, showing significant (p?<?0.05) accumulation of Pb in the above-ground biomass. Results obtained from Zn contaminated soils showed significant (p?<?0.05) accumulation in the above-ground compartments of T. diversifolia and H. annuus compared with root. However, the highest accumulation of Zn was observed in the leaf. The translocation factor and enrichment coefficient of Pb and Zn with these plant species are greater than 1, indicating that these metals moved more easily in these plants. However, this result also showed that the translocation of Zn from root to the shoot of the two plants was higher than Pb. In conclusion, this experiment showed that these plants accumulated substantial Pb and Zn in their shoots (leaf and stem) at 4 weeks AP which diminished with time. This implies that the efficiency of these plants in cleaning the contaminated soils was at the early stage of their growth.     

狼尾草等6种植物对十溴联苯醚污染土壤的生理响应及其修复效果

考察了狼尾草、龙葵、空心菜、苣菜、芥菜和鱼腥草6种植物对土壤中十溴联苯醚（BDE-209）的生理响应及其修复效果。结果表明,在BDE-209污染条件下,供试植物体内丙二醛（MDA）含量升高,表明植物受到一定的毒害作用,而在植物抗逆境机制作用下,植物体内可溶性蛋白质含量升高,超氧化物歧化酶（SOD）活性下降;在供试植物生物量方面,BDE-209对龙葵、空心菜和狼尾草地上部有促进作用,而对苣菜、芥菜具有一定的抑制作用;6种修复植物体内均检测出BDE-209,且地上部与根部BDE-209含量具有显著差异,其中狼尾草根部干重含量高达16.93mg·kg-1;修复60d后,土壤中BDE-209含量均有一定程度的下降,最高去除率可达40.44%,且根际土与非根际土BDE-209去除率有显著差异。修复效果依优劣次序为狼尾草〉龙葵、空心菜〉鱼腥草〉芥菜〉苣菜。     

株洲霞湾港域乡土植物及其根际土壤重金属蓄积特性

通过采样调查,对株洲霞湾港域9种乡土植物及其根际土壤的重金属含量进行研究,并对比分析植物对Cu、Cd、Pb、Zn的吸收、转运和富集特征.结果表明:该港域土壤中Cd、Pb、Zn的含量均超过国家土壤环境质量三级标准,存在严重的复合污染.采集的9种植物均对污染表现出一定的耐受性,且不同植物对重金属的吸收和转运表现出较大差异性,根据其生物富集系数和转运系数,大致可分为三类.广玉兰、何首乌、珊瑚树和野芋为富集型植物,适合种植于港堤附近的农田边、厂区;小叶女贞为根部囤积型植物,黄独、蓖麻、小构树和薏米为规避型植物,适合种植于荒地等利用价值低的地区.     

Heavy Metals in Soil, Plants and Groundwater Following High-Rate Sewage Sludge Application to Land

The concentrations, solubility and mobility of Cr, Cu, Ni, Pb and Zn were measured over a four year period in soil from a site that had received over 1000 t ha^-1 wet, undigested, sewage sludge (on average, 15% dry solids). The pH of this light-textured sandy soil was markedly reduced after sludge application (to ≤4 in some samples), presumably as a result of breakdown of the unstable organic matter, nitrification of the NH₄ ⁺-N and sulphide oxidation. As a consequence, soil solution concentrations of Cu, Ni, and especially, Zn were initially elevated, and this was reflected in high plant uptake of Zn and elevated levels of all three metals in some groundwater wells. An extensive liming programme resulted in soil pH values generally between 5 and 6, more normal for this soil, in the following years. Soil solution metal concentrations were substantially lower, e.g., Zn from a high of 27 mg kg^-1 in 1995 to 0.04 mg kg^-1 in the equivalent sample in 1999. Herbage Zn concentrations declined accordingly and overall there was a strong relationship between plant metal uptake and soil solution concentration of this element (R² = 0.84), although not for any of the other metals. Our results suggested that, for this soil, pH was by far the greatest determinant of metal solubility and that the metal source, whether sewage sludge or geochemical, had little influence. Results from extractants that solubilise other metal phases, i.e., NaNO₃, EDTA and HNO₃, are also presented and discussed.     

植物修复镉污染土壤的差异性研究

以茶花凤仙和百日草为供试植物,对不同镉浓度条件下两种植物的生物量、镉含量及其对镉的吸收、富集状况进行了研究.结果表明,不同程度镉浓度处理的土壤中生长的茶花凤仙和百日草对镉的吸收和富集特性不同,生物量随土壤镉浓度的升高而升高,但达到一定浓度时,生物量又随土壤镉浓度的升高而降低.茶花凤仙在低浓度区域,富集镉的能力要强于百日草,但是在高浓度区域时,茶花凤仙富集镉的效果却低于百日草的富集效果.本试验中所选的两种植物,百日草和茶花凤仙均没有达到超积累植物要求的标准.