Phytoremediation: European and American trends successes, obstacles and needs

Phytoremediation is an emerging technology based on the use of green plants to remove, contain, inactivate or destroy harmful environmental pollutants. Recent developments in Europe and the USA show that the approach is somewhat different on both sides of the Atlantic. In Europe, phytoremediation has more basically been research driven and, based on the outcomes, applications have been envisaged. By contrast, the approach in the USA is more application and experience driven. In spite of a growing track record of commercial success, more demonstration projects are needed to prove that phytoremediation is effective in order to rigorously measure its underlying economics, and to expand its applications. More fundamental research is also required to better understand the complex interactions between pollutants, soil, plant roots and micro-organisms at the rhizosphere level, to increase the bioavailability of pollutants, to fully exploit the metabolic diversity of plants and, thus, to successfully implement this new green technology.     

植物修复多环芳烃污染土壤的根际效应机制研究进展

多环芳烃类有机污染物在土壤中可长期存在,进而通过食物链对人类健康产生重大潜在风险。对多环芳烃污染土壤进行植物修复是一种环境友好且经济有效的污染补救策略。进行植物根际效应机制研究对于开发可持续性多环芳烃污染土壤的植物修复技术具有重要指导意义。对近年来的相关研究工作进行了总结,结果表明:多种禾本科植物具有较强的多环芳烃污染耐受性和较好的修复效能,利用多植物混植的联合修复方式表现出优于单一植物的修复优势。低分子量有机酸类根系分泌物通过与土壤中多环芳烃污染物形成反馈回路决定植物修复体系中多环芳烃的命运。修复植物根系分泌物可塑造特定的根际微生物区系,根际微生物可通过多种机制来降解土壤环境中的多环芳烃。针对在植物修复多环芳烃污染土壤研究过程中尚存在一些问题,提出了未来植物修复根际效应机理研究中应该关注的重点和方向,旨在为优化多环芳烃污染土壤植物修复技术提供科学依据与理论参考。     

Plant- and microbe-assisted biochar amendment technology for petroleum hydrocarbon remediation in saline-sodic soils: A review

Soil degradation through salinization and pollution by toxic compounds such as petroleum hydrocarbons(PHCs) in the coastal wetlands has become a significant threat to ecosystem health, biodiversity, and food security. However, traditional remediation technologies can generate secondary pollutants, incur high operating costs, and consume significant quantities of energy. Bioremediation, using plants, biochar, and microbes, is an innovative and cost-effective option to remediate contaminated soils. Biochar, as a plant/microbe growth enhancer, is a promising green approach for the sustainable phytoremediation of PHCs in salinized soils. This review therefore summarizes the effect of plant-and microbe-assisted biochar amendment technology for the remediation of PHCs and salinization. Plant-microbe interactions mediated rhizodegradation despite increasing hydrocarbon sorption. Overall, microbial respiration is more active in biochar amendments, due to faster biodegradation of PHCs and improved soil properties. The use of biochar, plants, and microbes is recommended,as it offers a practical and sustainable option, both ecologically and economically, for the remediation of PHCs and excess salinity. Further development of new green technologies is to be encouraged.     

天然有机添加物提高植物修复污染土壤效率：研究进展综述.

Environmental pollution caused by metals, radionuclides and organic pollutants affects quality of the biosphere: soil, water and air.Currently, great efforts have been made to reduce, remove or stabilize contaminants in polluted sites. There has been increasing interest in phytoremediation—the use of plants to reduce concentration of pollutants or to render them harmless. This paper provides a brief review of recent progress in the research and practical application of phytoremediation techniques. Improvements in phytoremediation due to utilization of organic amendments, namely, agro- and industrial wastes(such as sugar beet residue, composted sewage sludge or molasses), biochar, humic substances, plant extracts and exudates are discussed, as well as their influences on soil structure and characteristics, plants growth and bioavailability of pollutants. Both plant-assisted phytoremediation and the use of natural materials in the absence of remediating plant are believed to be cost-effective and environmentally friendly approaches for soil cleanup. However,the characterization and quantification of a range of natural materials used in phytoremediation are essential in order to implement these approaches to practice.     

治理环境污染的绿色植物修复技术

环境污染是全人类面临的重大挑战。植物修复技术的出现及逐步完善,为人类治理环境污染提供了新的思路。植物修复技术包括植物萃取、植物固定、植物降解、植物促进、根滤作用和利用植物去除大气污染物等类型。成本低廉、环境友好是该技术的优势,但修复周期长、污染物的生物有效性和毒性水平也限制了其应用。已知的大多数超富集植物生长缓慢、生物量小,是制约植物修复技术应用的瓶颈。为进一步提高植物修复技术的效率,未来研究应侧重于以下几个方向:分子生物学和基因工程技术在超累积植物品种培育中的应用,农事操作对植物修复技术的辅助作用,植物微生物联合修复技术在污染物吸收、转移和降解中的作用机制及应用,以及生物、物理和化学等多种修复措施的综合利用,同时开展大规模的田间验证试验,将植物修复与景观建设、生物质能利用以及观赏植物种苗生产相结合。     

Phytoremediation Technology: Hyper-accumulation Metals in Plants

This paper reviews key aspects of phytoremediation technology and the biological mechanisms underlying phytoremediation. Current knowledge regarding the application of phytoremediation in alleviating heavy metal toxicity is summarized highlighting the relative merits of different options. The results reveal a cutting edge application of emerging strategies and technologies to problems of heavy metals in soil. Progress in phytoremediation is hindered by a lack of understanding of complex interactions in the rhizosphere and plant based interactions which allow metal translocation and accumulation in plants. The evolution of physiological and molecular mechanisms of phytoremediation, together with recently-developed biological and engineering strategies, has helped to improve the performance of both heavy metal phytoextraction and phytostabilization. The results reveal that phytoremediation includes a variety of remediation techniques which include many treatment strategies leading to contaminant degradation, removal (through accumulation or dissipation), or immobilization. For each of these processes, we review what is known for metal pollutants, gaps in knowledge, and the practical implications for phytoremediation strategies.     

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。     

土壤中有机污染物的植物修复研究进展

植物修复是土壤有机污染物修复的有效途径之一，主要包括植物吸收、根际土壤酶促进降解和微生物对其的一系列降解。本文简述了植物修复的含义，系统综述了植物修复有机污染物的机理，并阐述了利用植物对农药、氯代化合物、多环芳烃和其它有机污染物进行修复的研究成果与应用，展望了今后进一步研究的重点。     

根际促生菌及其在污染土壤植物修复中的应用

植物对重金属吸收、转运和积累以及植物生物学特征使其成为修复重金属污染土壤的重要手段之一。然而,由于植物对重金属的耐受性有限而限制其广泛实际应用,因而探讨植物修复技术强化措施就显得尤为重要。随着自然资源的开发和技术的发展,微生物调控使植物修复技术变得更为可行和更有价值。回顾近年来新兴的微生物调控技术,植物根际促生菌资源因其对环境无污染,可利用自身的抗性系统减缓重金属对植物的毒性,促进植物的生长和影响重金属的迁移等优势,在修复过程中发挥着重要作用。目前,国内外就植物根际促生菌的筛选、鉴定和应用价值等方面已经做了大量的相关研究。本文综述了根际促生菌-植物相互作用的机制及其促进植物修复重金属污染土壤的作用原理。     

内生细菌强化重金属污染土壤植物修复研究进展

近年来,植物修复因其独特的优势备受推崇,尤其是当前植物内生细菌的应用为植物修复重金属污染土壤提供了有效的新方案.在植物修复过程中,耐重金属的内生细菌利用与植物的共生互惠关系,通过自身的抗性系统缓解重金属的毒性,促进植物对其迁移,并通过溶磷、固氮等途径改善植物营养以及分泌植物激素、铁载体、特异性酶、抗生素等作用,促进植物在逆境条件下的生长和对重金属的富集.本文综述了近年来国内外关于重金属抗性植物内生细菌促进植物生长、增强植物对重金属的抗性以及影响重金属在植物体内吸收、转运和积累的作用机制,系统分析了内生细菌促进植物修复重金属污染土壤的机理,并进一步讨论了植物内生细菌在重金属污染土壤植物修复工程中的应用前景与研究方向.     

表面活性剂对植物修复有机污染土壤的增效作用及原理

Phytoremediation is becoming a cost-effective technology for the in-situ clean up of sites polluted with hydrophobic organic contaminants （HOCs）. The major factors limiting phytoremediation are the mass transfer, rate of plant uptake, and microbial biodegradation of HOCs. This article discusses the potential of surfactants to enhance desorption, plant uptake, and biodegradation of HOCs in the contaminated sites. Positive effects of surfactants on phytoremediation have been recently observed in greenhouse studies. The presence of some nonionic surfactants including polyoxyethylene sorbltan monooleate （Tween 80） and polyoxyethylene（23）dodecanol （Brij35） at relatively low concentrations resulted in significant positive effects on phytoremediation for pyrene-contaminated soil. However, the anionic surfactant （sodium dodecyl sulfate, SDS） and the cationic surfactant （cetyltrimethylammonium bromide, CTMAB） were not useful because of their phytotoxicity or low efficiency for surfactant-enhanced phytoremediation （SEPR）. The mechanisms of SEPR for HOC-contaminated sites were evaluated by considering experimental observations. In view of concerns about the cost effectiveness and toxicity of surfactants to plants, more research is needed to enhance the use of SEPR technology.     

接种密度对植物生长及烃降解的影响

The combined use of plants and bacteria is a promising approach for the remediation of soil contaminated with organic pollutants. Different biotic and abiotic factors can affect the survival and activity of the applied bacteria and consequently plant growth and phytoremediation efficiency. The effect of inoculum density on the abundance and expression of alkane-degrading genes in the rhizosphere of plant vegetated in hydrocarbon-contaminated soil has been rarely observed. In this study, an alkane-degrading bacterium (Pantoea sp. strain BTRH79), at different inoculum densities (10⁵ to 10⁸ cells cm^-3 soil), was inoculated to ryegrass (Lolium perenne) vegetated in diesel-contaminated soil to find the optimum inoculum density needed for its efficient colonization and hydrocarbon degradation activity. Bacterial inoculation improved plant growth and hydrocarbon degradation. Maximum plant growth and hydrocarbon degradation wwereobserved with the inoculum having the highest cell density (10⁸ cells cm^-3 soil). Moreover, the inoculum with higher cell density exhibited more abundance and expression of alkane hydroxylase gene, CYP153. This study suggests that the inoculum density is one of the main factors that can affect bacterial colonization and activity during phytoremediation.     

转基因植物修复重金属污染土壤研究进展

通过基因工程技术提高植物对金属的耐性,增加金属在植物体内的累积被认为是进行污染土壤生态恢复以及减少食物链金属污染的一条切实可行的有效途径。随着细胞和分子水平上对金属在植物体内的新陈代谢机理的认识及相关基因的不断鉴定,应用转基因技术提高植物对重金属的耐性和积累量的研究已取得了一些进展。本文就近年来分子水平上植物体内金属新陈代谢机理及基因技术在植物修复重金属污染方面的研究进展进行综述。     

植物修复金属污染土壤上丛枝菌根真菌与植物之间的交互作用

Metal contamination in the environment is a global concern due to its high toxicity to living organisms and its worldwide distribution.The principal goal of this review is to examine the current strategies and technologies for the remediation of metalcontaminated soils by metal-accumulating plants and assess the roles of arbuscular mycorrhizal(AM)fungi in remediation of soils under hyperaccumulator or non-accumulator plants.The use of plants to remove metals from the environment or reduce the toxicity,known as phytoremediation,is an environmentally sustainable and low cost remediation technology.The mechanisms of the use of hyperaccumulator plants for phytoremediation included solubilization of the metal in the soil matrix,the plant uptake of the metal,detoxification/chelation and sequestration,and volatilization.Recently,some ecologists have found that phytoremediation with the aids of mycorrhizae can enhance efciency in the removal of toxic metals.AM fungi can facilitate the survival of their host plants growing on metal-contaminated land by enhancing their nutrient acquisition,protecting them from the metal toxicity,absorbing metals,and also enhancing phytostabilization and phytoextraction.Such information may be useful for developing phytoremediation program at metal-contaminated sites.     

铀对植物的胁迫效应研究进展

铀是一种具有较高化学毒性的放射性核素。铀矿开采、核事故泄露、核废物的不恰当处理等会对周围土壤造成放射性污染。植物体内富集的铀可通过食物链进入人体,从而对人体健康造成伤害。国内外学者针对铀污染土壤的植物修复技术开展了一系列研究工作。本研究系统地总结了铀对植物胁迫效应的研究进展,主要包括铀对植物生长发育、生理生化、基因毒害、水分代谢和营养代谢等方面的影响。并结合当前研究现状,对未来的研究方向进行了展望。本研究结果为进一步阐释富集植物对铀的吸收和转运机制,以及铀污染土壤的植物修复提供了理论依据,对于监测治理铀污染土壤和保护生态环境具有重要意义。     

土壤有机污染物电化学修复技术研究进展

综述了有机污染土壤的电动力修复和微生物电化学修复的最新研究进展。分析了电动力修复中电极材料、运行条件等因素对污染物去除效果的影响,总结了添加表面活性剂、引入具有降解能力的基质、与化学或生物联合等方式对土壤修复效果的强化作用,阐述了微生物电化学修复的效果、影响因素和微生物群落演变的规律。电化学技术能够有效去除土壤中的有机污染物,且电动力较微生物电化学具有更好的去除效果。为了实现电化学技术在污染土壤修复中的应用,未来需要从土壤导电性、电极材料以及反应器构型等方面优化以提高修复效果;此外,电化学修复技术的机理、功能微生物的群落特征研究等也是下一步研究的重点。     

农药污染土壤的植物修复研究进展

植物修复是土壤农药污染修复的有效途径之一。植物主要通过直接吸收和代谢、根际土壤植物酶促降解和根际微生物对污染物的降解等三种机制去除土壤中残留的农药。本文简述了植物修复的含义和优点,系统地综述了植物修复农药污染土壤的机理,阐述了利用植物对农药污染土壤进行修复的研究成果和应用,并展望了今后需要进一步研究的领域。     

Use of White Lupin Plant for Phytostabilization of Cd and As Polluted Acid Soil

Cadmium and arsenic are two of the most important and toxic pollutants ubiquitous in the environment. The occurrence of numerous polluted areas as the affected by the accident of Aznalcóllar pyrite mine has promoted the employment of the phytoremediation as a feasible technology able to control and reduce the risk of this contamination at low cost. White lupin plant is proposed as a candidate for phytoremediation. This work aims to study if it is possible to use white lupin in phytoremediation of soils affected by acid pyrite sludge, with simultaneous As and Cd pollution. Pot and field experiments with sludge-affected soil were carried out. The pot trial showed that the NTA treatment increased Cd and As concentrations in lixiviates, exceeding the maximum permissible levels, so that its use in field experiments was avoided. In the field experiment, phytoextraction of Cd and As by lupin plants was very low, suggesting that it was not recommended for phytoextraction. However, lupin culture in the field produced several benefits as: increase of acid soil pH probably by citrate excretion, decrease in soluble As and Cd fractions in soil, high concentration of As and Cd in roots with accumulation of heavy metals in root nodules. All these results support the use of Lupinus albus for phytostabilization and revegetation of the spill polluted soils.     

土壤污染物临界负荷研究进展

随着城市化进程与工农业的快速发展,土壤污染形势也越来越严峻。土壤污染物临界负荷的研究,可获取土壤可持续发展质量指标,是一条实现土壤可持续管理的有效途径。我国土壤污染临界负荷研究不足,为了推动其发展,本文讨论了其研究进展、指导原则、应用、存在问题与发展趋势。动态的和基于风险的土壤污染物临界负荷估算已是国际发展趋势。当前,缺乏完善的动态临界负荷估算模型,估算过程具有较大不确定性。为了准确地估算土壤污染物的临界负荷,在未来研究中需要加强对临界浓度制定和动态模型构建的研究,主要包括土壤中污染物的迁移传输规律、污染物的剂量-效应关系等。     

Aspects of phytoremediation of organic pollutants

Phytoremediation is a quite novel technique to clean polluted soils using plants. In theory, phytoremediation methods are cheap, are accepted by the public and, compared to physical or chemical approaches, are ecologically advantageous. Until today, however, there are only a few examples of successful applications. One reason is that the processes involved are complex, and a full clean up may require many years. Plants affect the water balance of a site, they change redox potential and pH, and stimulate microbial activity of the soil. These indirect influences may accelerate degradation in the root zone or reduce leaching of compounds to groundwater. Compounds taken up into plants may be metabolised, accumulated, or volatilised into air. Based on these processes, several phytoremediation methods have been developed: Phytoextraction, rhizofiltra-tion, phytostabilisation, rhizo and phytodegradation, pump and tree, land farming, phytovolatilisation, hydraulic control and more. Already in use are plants (and here willow, poplar and grass) for the degradation of petroleum products, aromatic hydrocarbons (BTEX), chlorinated solvents, explosives and cyanides. However, phytotoxicity and pollutant mass balances were rarely documented. Often, the success of the projects was not controlled, and only estimates can be made about the applicability and the potential of phytoremediation. This lack of experience about possibilities and limitations seems to be a hindrance for a broader use of these techniques.