上海市中小型河道沉积物和水生植物中重金属累积特征研究

采用野外调查和室内分析相结合的方法,以上海市8个区县25条中小型河道为研究对象,调查研究重金属在沉积物和水生植物中累积特征,采用潜在生态风险指数评价法对沉积物重金属污染进行了评价,采用生物富集系数(BCF)方法评价不同水生植物对重金属的富集特性,对水生植物与沉积物中的重金属含量进行相关性分析。分析表明,与土壤环境质量国家二级标准(GB15618-1995)相比,As、Ni和Zn平均含量是标准的6.7倍、1.5倍和1.4倍,Cd、Pb、Cu、Cr平均含量不超标。参照上海市土壤环境背景值,上海市中小型河道沉积物中7种重金属的潜在生态风险依次为:CdAsPbNiCuZnCr,其中Cd、As生态风险严重,7种潜在生态风险Ri平均值为431.43,有强生态风险。植物体内累积最高的重金属为Cu,累积最低的重金属为Cd,沉水植物体内重金属Cd、As、Cr、Pb、Ni、Cu的含量均大于挺水植物,沉水植物苦草和水盾草对多种重金属的富集能力大于1,在重金属复合污染水体修复中具有较大潜力。根据植物体与沉积物中重金属的含量关系,发现黑藻与沉积物中重金属Cu、Ni、Pb的含量显著正相关;水盾草与沉积物中重金属Cu含量显著正相关,芦苇与沉积物中重金属Cr的含量显著正相关,上述3种植物可作为上海市河道重金属污染监测植物的选择对象。     

上海市中小型河道沉积物和水生植物中重金属累积特征研究

采用野外调查和室内分析相结合的方法,以上海市8个区县25条中小型河道为研究对象,调查研究重金属在沉积物和水生植物中累积特征,采用潜在生态风险指数评价法对沉积物重金属污染进行了评价,采用生物富集系数(BCF)方法评价不同水生植物对重金属的富集特性,对水生植物与沉积物中的重金属含量进行相关性分析。分析表明,与土壤环境质量国家二级标准(GB15618-1995)相比,As、Ni和Zn平均含量是标准的6.7倍、1.5倍和1.4倍,Cd、Pb、Cu、Cr平均含量不超标。参照上海市土壤环境背景值,上海市中小型河道沉积物中7种重金属的潜在生态风险依次为：Cdgt;Asgt;Pbgt;Nigt;Cugt;Zngt;Cr,其中Cd、As生态风险严重,7种潜在生态风险Ri平均值为431.43,有强生态风险。植物体内累积最高的重金属为Cu,累积最低的重金属为Cd,沉水植物体内重金属Cd、As、Cr、Pb、Ni、Cu的含量均大于挺水植物,沉水植物苦草和水盾草对多种重金属的富集能力大于1,在重金属复合污染水体修复中具有较大潜力。根据植物体与沉积物中重金属的含量关系,发现黑藻与沉积物中重金属Cu、Ni、Pb的含量显著正相关;水盾草与沉积物中重金属Cu含量显著正相关,芦苇与沉积物中重金属Cr的含量显著正相关,上述3种植物可作为上海市河道重金属污染监测植物的选择对象。     

三里七湖水生植物重金属富集作用研究

通过野外采样和实验分析,研究了黄石市三里七湖流域中的底泥、水样和九种水生植物的Cr、Cu、Mn、Pb、Zn五种重金属的含量及其在植物体内的富集特征。测定分析结果表明:底泥的重金属含量严重超标,Cr、Cu、Mn、Pb、Zn五种重金属的含量分别达到国家标准值的1.43、6.40、1.64、3.33、9.65倍。水体中的重金属Cr、Pb、Zn分别超过了国家标准值的22.3、9.0、1.35倍,Cu、Mn达标。香蒲、水芹菜、水花生、黑三棱、水蓼、菰和狐尾藻中Zn的含量最高,Cu含量最低;芦苇的Pb含量最高,Cr的含量最低;菹草的Mn含量最高,Cu含量最低。同一水生植物对不同的重金属富集作用具有选择性;而不同的水生植物对同一重金属的富集能力存在较大的差异性;水生植物中的香蒲、芦苇、菰、狐尾藻等可作为重金属复合污染流域水体的修复植物。     

贵州木油厂汞矿区4种藓类植物及其基质中重金属元素分析

通过对贵州木油厂汞矿区4种藓类植物(真藓、卵蒴真藓、羽枝青藓和圆枝粗枝藓)及其生长基质中的Cu、Zn、Ca、Mg、Cd、Pb、Hg、As 8种元素进行测定分析,以揭示藓类植物与生长基质中重金属元素及其污染程度的关系.结果表明:(1)贵州木油厂汞矿区藓类植物生长基质中Cu、Hg和As元素的平均含量分别是相应国标值的1.29倍、300倍和1.69倍,说明该矿区已受到Cu、Hg和As的污染,且Hg污染特别严重.(2)羽枝青藓的As、Zn、Cd和Pb含量均最高,圆枝粗枝藓的Cu、Ca、Mg和Hg含量均最高,对重金属具有较强的耐受性.(3)羽枝青藓和圆枝粗枝藓对Zn均强烈富集,其富集系数分别为6.14和3.364;羽枝青藓、卵蒴真藓和真藓对Pb均强烈富集,其富集系数分别为13.769、9.547和3.004;表明羽枝青藓对Zn和Pb的富集能力最强,可用于土壤Zn和Pb的污染治理.(4)4种藓类植物对Cu 的富集系数为0.915～1.184,卵蒴真藓和圆枝粗枝藓对Hg的富集系数分别为0.542和0.682,圆枝粗枝藓对As的富集系数为0.74,均为同一水平,表明4种藓类植物可指示其生长基质中Cu、Hg和As的含量.(5)元素间的相关分析显示,木油厂汞矿的Cd和As之间呈显著负相关(P＜0.05),表明两元素间有拮抗作用.     

包头南海子湿地三种鹭鸟羽毛与环境中重金属含量的关系

于2016年7至10月采用电感耦合等离子体发射光谱法(ICP-OES),测定了内蒙古包头南海子湿地繁殖期过后的白琵鹭(Platalea leucorodia)、苍鹭(Ardea cinerea)和夜鹭(Nycticorax nycticorax)3种鹭鸟初级飞羽及环境因子(水、土壤、食物)中As、Cd、Cr、Cu、Ni、Pb、Zn、Fe、Mn、Hg 10种重金属的含量,采用单因素方差分析方法比较了不同鹭鸟种类羽毛重金属含量差异,并通过生物富集系数及Pearson相关性检验分析了羽毛与环境因子间重金属含量之间的关系,以揭示包头南海子湿地环境中重金属污染现状及生物富集特征。结果表明:(1)被检测的10种重金属中,As、Cd、Cr、Cu、Pb、Zn、Hg 7种元素在湿地环境中均已超标,尤其土壤中Fe、Zn、Cu已达到重度污染的程度。(2)不同重金属元素在鹭鸟羽毛中的含量存在差异,其中Fe元素在白琵鹭羽毛中的含量水平最高(388.77 mg/kg),Cd元素在夜鹭羽毛中的含量最低(0.12 mg/kg)。在鹭鸟羽毛中重金属含量由高至低的顺序分别为,白琵鹭Fe、Zn、Mn、Cu、Hg、Cr、Ni、Pb、As、Cd,苍鹭Zn、Fe、Cu、Cr、Ni、As、Mn、Hg、Pb、Cd,夜鹭Zn、Fe、Mn、Cu、Ni、Pb、Hg、Cr、As、Cd。除Pb和Cd元素外,其他8种元素含量在3种鹭鸟羽毛中的含量种间差异显著。(3)相关分析表明,鹭鸟羽毛中的重金属含量与环境因子中的重金属含量显著相关且呈现富集特征,为此可作为监测当地环境污染的指示性材料。     

八种水生植物对重金属富集能力的比较研究

通过野外采样和系统分析方法,研究了芜湖市四褐山工业区附近水域中Cu、Pb、Cd、Zn和Mn5种重金属的含量及其在8种水生植物体内的积累特性。结果表明,工业区水体污染严重,重金属含量严重超标,分别为标准值的9、10.1、400、3和438倍;8种水生植物的重金属积累量均较大,其中以水鳖根、茎叶的Cu、Pb、Cd、Zn含量最高,分别为水体中重金属浓度的9.12和2.59倍、33.41和5倍、0.8和0.3倍、26.9和9.1倍,明显高于其它7种水生植物;8种水生植物不同器官对Cu、Pb、Zn的富集系数均>1,富集能力较强。其中,香蒲对Pb、Cd的吸收能力表现为茎叶>根。结果表明,在Cu、Pb和Zn等重金属复合污染水域的植物治理中,浮萍、香蒲、水鳖、中华慈姑、芦苇、空心莲子草等植物有着较大的发展潜力和应用前景。     

不同土壤生境下斑茅对重金属的富集特征

为了筛选Cu、Zn、Pb、Cd多重金属离子的富集植物,对不同土壤生境(铜铁矿、钨矿、铅锌矿和无矿场污染)的优势种斑茅(Saccharum arundinaceum(Retz.)Jeswiet)对Cu、Zn、Pb、Cd离子富集情况进行了调查。结果表明,斑茅对Cu、Zn、Pb、Cd离子有富集优势并以Cu富集显著,斑茅根系土壤与斑茅地上部Cu含量存在相关性(P<0.05),斑茅对Pb和Cd的富集与转运存在极显相关性(P<0.01);在强酸、多金属污染弃耕农田土壤中,斑茅不仅符合Cu超富集植物的特征,而且其对Zn、Pb和Cd3种重金属的富集系数和转运系数均>1。在Cd、Cu、Pb和Zn均低于国家土壤环境质量二级标准(GB15618-1995)的弃耕农田中,斑茅对Cu、Zn和Cd的富集系数均>1。研究表明,斑茅可以作为Cu、Zn、Pb、Cd多金属污染土壤的富集植物进行人工修复。     

公路绿化植物油松(Pinus tabulaeformis)和小叶杨(Populus simonii)对重金属元素的吸收与积累

对内蒙古西部公路绿化植物油松（Pinus tabulaeformis）、小叶杨（Populus simonii）及其根际土壤中重金属元素（Cd、Hg、Pb、Cu、Zn、Ni、Cr）和类金属元素（As和Se）含量以及根际土壤重金属（Cu、Zn、Pb、Ni和Cr）形态、土壤pH值进行了测定。对比分析了公路沿线不同绿化植物及其不同器官对重金属元素的吸收与积累特征。结果表明：绿化植物根际土壤对重金属元素的吸附及污染程度以Cd为最高。随原子序数的递增,小叶杨和油松两种植物的根部和茎叶两种营养器官中重金属的含量均表现出“N”字形变动趋势。而且重金属元素在不同植物不同器官中的含量具有Zn〉Cu〉Ni,Cr,As,Pb〉Cd〉Hg的基本规律。小叶杨茎叶对重金属元素Cr、Ni和Pb的富集能力较根部为强,油松茎叶对重金属元素Cr、Ni、Cu和Pb的富集能力较根部为强。绿化植物根际土壤重金属元素有效态占总量百分比的大小序列为Zn〉Pb〉Ni、Cr〉Cu,与重金属元素在不同植物不同器官中的含量大小序列Zn〉Cu〉Ni、Cr、As、Pb〉Cd〉Hg并非趋于一致。公路绿化植物对根际土壤中重金属元素的吸收和积累与重金属元素有效态所占的比例有关。     

红枫湖富营养化水体生态修复中水生植物化学成分

高原山区深水型湖泊水深大、水位变化剧烈,不利于水生植物生长,通常的浅水湖泊生态修复技术难以应用.本文选取贵州红枫湖这一典型的高原深水湖泊作为试验点,在右二湖湾以浮岛为载体引种多种水生植物,并对植物根茎叶中的氮、磷及重金属成分进行了分析.结果表明:各水生植物氮含量为菹草＞鲁梅克斯＞聚合草,磷含量为菹草＞伊乐藻＞鲁梅克斯,氮、磷元素去除效果较好的植物为菹草、伊乐藻、鲁梅克斯;试验植物对重金属Cu、Cd、Pb、Zn和Hg均具有一定的耐受性,植物内不同重金属的累积浓度为Zn＞Pb＞Cu＞＞Cd＞Hg,重金属富集系数根＞叶＞茎,Zn/Cd比值为叶＞茎＞根;总体上,黑麦草、鲁梅克斯和菹草重金属的富集系数较高;植物中总氮(TN)与总磷(TP)含量呈显著正相关,重金属与营养元素之间不存在明显的相关性.试验表明,陆生植物依靠浮岛载体能在水面较好地生长,可应用于深水型湖泊污染水体生态修复.在实际应用时,需结合水体污染特点和植物吸收特性选择最佳植物组合类型.     

广东大中型水库底泥重金属含量特征及潜在生态风险评价

广东省45宗大中型水库底泥重金属含量分析评价结果表明:除Cr外,广东省大中型水库底泥中Cu、Zn、Pb和Cd含量均高于广东省土壤重金属含量背景值.广东省四大地理区域中,粤北地区大中型水库底泥Cu、Zn、Pb和Cd平均含量均为最高,分别为89.71、321.21、154.95mg/kg和1.46mg/kg;其次是粤东和粤中地区;粤西大中型水库底泥Cu、Zn、Pb和Cd平均含量均为最低,但Cr平均含量居四大区域之首,为130.81mg/kg.粤东和粤北大中型水库底泥重金属富集系数以Cd最高;粤中和粤西大中型水库底泥重金属富集系数则以Cu最大.总体而言,粤北大中型水库底泥重金属具有很强的潜在生态风险,粤东和粤中大中型水库底泥重金属潜在生态风险程度为中等;粤西大中型水库底泥重金属属于轻微生态风险程度.结果说明,广东省大部分地区大中型水库底泥的重金属潜在生态风险主要是由于底泥中Cd的潜在生态风险系数过高所造成.人为生产活动,特别是矿产开采造成的污染是广东省大中型水库底泥重金属潜在生态风险等级提高的主要原因.     

超富集植物吸收富集重金属的生理和分子生物学机制

与普通植物相比,超富集植物在地上部富集大量重金属离子的情况下可以正常生长,其富集重金属的机理已经成为当前植物逆境生理研究的热点领域．尤其是近两年,随着分子生物学等现代技术手段的引人,关于重金属离子富集机理的研究取得了一定进展．通过与酵母突变株功能互补克隆到了多条编码微量元素转运蛋白的全长cDNA;也从分子水平上研究了谷胱甘肽、植物螯合素、金属硫蛋白、有机酸或氨基酸等含巯基物质与重金属富集之间的可能关系．本文从植物生理和分子生物学角度简要评述超富集植物对重金属元素的吸收、富集、整合及区室化的机制．     

Plant and rhizosphere processes involved in phytoremediation of metal-contaminated soils

This paper reviews the recent advances in understanding of metal removal from contaminated soils, using either hyperaccumulator plants, or high biomass crop species after soil treatment with chelating compounds. Progress has been made at the physiology and molecular level regarding Zn and Ni uptake and translocation in some hyperaccumulators. It is also known that natural hyperaccumulators do not use rhizosphere acidification to enhance their metal uptake. Recently, it has been found that some natural hyperaccumulators proliferate their roots positively in patches of high metal availability. In contrast, non-accumulators actively avoid these areas, and this is one of the mechanisms by which hyperaccumulators absorb more metals when grown in the same soil. However, there are few studies on the exudation and persistence of natural chelating compounds by these plants. It is thought that rhizosphere microorganisms are not important for the hyperaccumulation of metals from soil. Applications of chelates have been shown to induce large accumulations of metals like Pb, U and Au in the shoots of non-hyperaccumulators, by increasing metal solubility and root to shoot translocation. The efficiency of metal uptake does vary with soil properties, and a full understanding of the relative importance of mass flow and diffusion in the presence and absence of artificial chelates is not available. To successfully manipulate and optimise future phytoextraction technologies, it is argued that a fully combined understanding of soil supply and plant uptake is needed.     

The Phylogenetic Association Between Salt Tolerance and Heavy Metal Hyperaccumulation in Angiosperms

Salt tolerance and heavy metal hyperaccumulation are two rare plant abilities that are heavily studied for their potential to contribute to agricultural sustainability and phytoremediation in response to anthropogenic environmental change. Several observations suggest that it is worth investigating the link between the abilities to tolerate high levels of soil salinity or accumulate more of a particular heavy metal from the soil than most plants. Firstly, several angiosperm families are known to contain both salt tolerant plants (halophytes) and heavy metal hyperaccumulators. Secondly, some halophytes can also accumulate heavy metals. Thirdly, although salinity tolerance and heavy metal hyperaccumulation typically require many physiological or anatomical changes, both have apparently evolved many times in angiosperms and among closely related species. We test for a significant relationship between halophytes and hyperaccumulators in angiosperms using taxonomic and phylogenetic analyses. We test whether there are more angiosperm families with both halophytes and hyperaccumulators than expected by chance, and whether there are more species identified as both halophyte and hyperaccumulator than if the abilities were unconnected. We also test whether halophytes and hyperaccumulators are phylogenetically clustered among species in seven angiosperm families. We find a significant association between halophytes and hyperaccumulators among angiosperm families and that there are significantly more species identified as both halophytes and hyperaccumulators than expected. Halophytes and hyperaccumulators each show low phylogenetic clustering, suggesting these abilities can vary among closely related species. In Asteraceae, Amaranthaceae, Fabaceae, and Poaceae, halophytes and hyperaccumulators are more closely related than if the two traits evolved independently.     

Opportunities and feasibilities for biotechnological improvement of Zn, Cd or Ni tolerance and accumulation in plants

Metals contaminate the soil when present in high concentrations causing soil and ultimately environmental pollution. “Phytoremediation” is the use of plants to remove pollutants from contaminated environments. Plants tightly regulate their internal metal concentrations in a process called “metal homeostasis”. Some species have evolved extreme tolerance and accumulation of Zn, Cd and Ni as a way to adapt to exposure to these metals. Such traits are beneficial for phytoremediation, however, most natural metal hyperaccumulator species are not adapted to agriculture and have low yields. A wealth of knowledge has been generated regarding metal homeostasis in plants, including hyperaccumulators, which can be used in phytoremediation of Zn, Cd and Ni. In this review, we describe the current state of Zn, Cd and Ni physiology in plants and the underlying molecular mechanisms. The ways to efficiently utilize this information in designing high biomass metal accumulator plants are discussed. The potential and application of genetic modification has extended our understanding about the mechanisms in plants dealing with the metal environment and has paved the way to achieve the goal of understanding metal physiology and to apply the knowledge for the containment and clean up of metal contaminated soils.     

Metal ion ligands in hyperaccumulating plants

Metal-hyperaccumulating plants have the ability to take up extraordinary quantities of certain metal ions without succumbing to toxic effects. Most hyperaccumulators select for particular metals but the mechanisms of selection are not understood at the molecular level. While there are many metal-binding biomolecules, this review focuses only on ligands that have been reported to play a role in sequestering, transporting or storing the accumulated metal. These include citrate, histidine and the phytosiderophores. The metal detoxification role of metallothioneins and phytochelatins in plants is also discussed.     

Phytoremediation of Metal-Polluted Ecosystems: Hype for Commercialization

Air, water, and soil are polluted by a variety of metals due to anthropogenic activities, which alter the normal biogeochemical cycling. Biodiversity has been employed widely by both developed and developing nations for environmental decontamination of metals. These technologies have gained considerable momentum in the recent times with a hype for commercialization. The United States Environmental Protection Agency's remediation program included phytoremediation of metals and radionuclides as a thrust area to an extent of 30% during the year 2000. Plants, that hyperaccumulate metals, are the ideal model organisms and attracted attention of scientists all over the world for their application in phytoremediation technology. Metal hyperaccumulators have the ability to overcome major physiological bottlenecks. The potential of hyperaccumulators for phytoremediation application relies upon their growth rates (i.e., biomass production) and metal accumulation rate (g metal per kg of plant tissue). The two primary reasons, that are limiting global application of this technology, are the slow growth rates exhibited by most naturally occurring metal hyperaccumulators and the limited solubility of metals in soils (i.e., the high affinity of metal ions for soil particles). Phytoremediation applications, relevance of transgenic plants for metal decontamination, chelate enhanced phytoremediation, chemical transformation, molecular physiology and genetic basis of metal hyperaccumulation by plants, commercialization hype for the phytoremediation technology are reviewed.     

环境重金属污染的植物修复及基因工程在其中的应用

随着工业技术的发展,重金属在土壤和水体中的含量越来越高,重金属污染已日益成为威胁人类健康和人类生活质量的严重的社会问题和环境问题。植物修复可部分解决这一问题且正引起人们的普遍关注。但现在发现许多用于修复的超量积累植物生长缓慢、植株矮小、地上部生物量小,成了实际应用中的最大限制。利用基因工程手段改变植物对重金属吸收、转运、积累和忍耐的机制,从而提高植物对重金属的富集能力,将成为今后植物修复领域研究的一个重要方向。     

Phytoextraction of metals and metalloids from contaminated soils

The removal of inorganic contaminants by plants is termed phytoextraction. Recent studies have looked at the feasibility of phytoextraction, and demonstrate that both good biomass yields and metal hyperaccumulation are required to make the process efficient. Adding chelating agents to soil to increase the bioavailability of contaminants can sometimes induce hyperaccumulation in normal plants, but may produce undesirable environmental risks. Thus, it is necessary to investigate the mechanisms responsible for hyperaccumulation, using natural hyperaccumulators as model plant species. Recent advances have been made in understanding the mechanisms responsible for hyperaccumulation of Zn, Cd, Ni and As by plants. Attempts to engineer metal tolerance and accumulation have so far been limited to Hg, As and Cd, and although promising results have been obtained they may be some way from practical application. More fundamental understanding of the traits and mechanisms involved in hyperaccumulation are needed so that phytoextraction can be optimised.     

Tolerance to cadmium in plants: the special case of hyperaccumulators

On sols highly polluted by trace metallic elements the majority of plant species are excluders, limiting the entry and the root to shoot translocation of trace metals. However a rare class of plants called hyperaccumulators possess remarkable adaptation because those plants combine extremely high tolerance degrees and foliar accumulation of trace elements. Hyperaccumulators have recently gained considerable interest, because of their potential use in phytoremediation, phytomining and biofortification. On a more fundamental point of view hyperaccumulators of trace metals are case studies to understand metal homeostasis and detoxification mechanisms. Hyperaccumulation of trace metals usually depends on the enhancement of at least four processes, which are the absorption from the soil, the loading in the xylem in the roots and the unloading from the xylem in the leaves and the detoxification in the shoot. Cadmium is one of the most toxic trace metallic elements for living organisms and its accumulation in the environment is recognized as a worldwide concern. To date, only nine species have been recognized as Cd hyperaccumulators that is to say able to tolerate and accumulate more than 0.01 % Cd in shoot dry biomass. Among these species, four belong to the Brassicaceae family with Arabidopsis halleri and Noccaea caerulescens being considered as models. An update of our knowledge on the evolution of hyperaccumulators will be presented here.     

Prospecting for hyperaccumulators of trace elements: a review

Specific plant species that can take up and accumulate abnormally high concentrations of elements in their aboveground tissues are referred to as “hyperaccumulators”. The use of this term is justified in the case of enormous element-binding capacity of plants growing in their natural habitats and showing no toxicity symptoms. An increasing interest in the study of hyperaccumulators results from their potential applications in environmental biotechnology (phytoremediation, phytomining) and their emerging role in nanotechnology. The highest number of plant species with confirmed hyperaccumulative properties has been reported for hyperaccumulators of nickel, cadmium, zinc, manganese, arsenic and selenium. More limited data exist for plants accumulating other elements, including common pollutants (chromium, lead and boron) or elements of commercial value, such as copper, gold and rare earth elements. Different approaches have been used for the study of hyperaccumulators – geobotanical, chemical, biochemical and genetic. The chemical approach is the most important in screening for new hyperaccumulators. This article presents and critically reviews current trends in new hyperaccumulator research, emphasizing analytical methodology that is applied in identification of new hyperaccumulators of trace elements and its future perspectives.