重金属污染生态学研究现状与展望

重金属污染生态学的研究迄今已有近 5 0 a的历史 ,在土壤重金属元素背景值和环境标准的制定、重金属在环境中的迁移转化、重金属污染治理、元素分析测定方法和规范、对生物体的毒性及生物体的响应等方面取得了很多研究成果 ,出版了很多专著。在对重金属污染生态学研究进行简要回顾的基础上 ,以重金属在生物体内的行为特征 (吸收、迁移、富集、毒害、解毒和抗性等 )为主线 ,从微观和宏观水平 ,系统综述了目前该领域的研究现状 ,分析了尚存在的一些问题 ,最后从生物对重金属污染适应的分子机理、治理方法和技术的创新性、复合污染下环境标准制定的科学化以及重金属污染条件下全球生物进化的趋势预测等方面作了研究展望     

海南万宁海域海洋生物重金属分析与评价

海洋经济生物体内重金属含量直接影响到人类健康。根据2020年12月对万宁海域12个调查站、10种生物(鱼类7种、软体类1种、甲壳类2种)体内的7种重金属(Cu、Pb、Zn、Cd、Cr、As、Hg)含量监测结果,分析了重金属的含量特征,并分别利用单因子污染指数法和重金属富集系数对重金属污染水平和它在生物体内的富集情况进行了评价。结果表明:(1)各类生物体内重金属含量的高低顺序不一致,但三类生物体内锌和铜的含量均相对较高。生物对必需元素锌和铜的富集明显高于对非必需元素铅、镉和总汞的,主动吸收能力明显。(2)不同类生物同种重金属的含量存在一定差异,甲壳类的高于鱼类和软体类的。万宁海域鱼类和软体类生物重金属单因子污染指数均小于1,部分甲壳类生物的铬单因子污染指数大于1,超标率为41.7%。铬是万宁海域海洋生物的主要污染因子,影响其含量的原因可能是周围的围填海工程,以及所研究物种的生理特性。(3)万宁海域甲壳类生物体内总汞已呈轻污染状态,铬呈重污染状态。(4)甲壳类生物对重金属的富集能力强于鱼类和软体类的,各类生物对Cu的富集能力最高,对As的富集能力最低,且对重金属Cu、Cd和Zn有潜在的严重...     

重金属污染影响植食性昆虫的研究进展

重金属污染是世界各国面临的最为棘手的问题之一,对生态系统和食品安全构成了严重威胁。作为生态系统中食物链和食物网的重要环节,植食性昆虫是环境中重金属迁移、积累的重要媒介,其因重金属污染而受到的影响引起了大家的关注。本文综述了从2007至2018年重金属污染对植食性昆虫影响的研究进展。昆虫受重金属胁迫的研究途径有人工饲料添加、野外田间暴露、“土壤-植物-昆虫”食物链传递以及体外注射等。积累在植食性昆虫体内的过量重金属可导致其存活率、繁殖力和种群增长率降低,生长发育迟缓。重金属污染对植食性昆虫的生理生化毒性包括细胞超微结构破坏和DNA损伤,体内能量物质含量降低,酶活性、基因表达改变等。植食性昆虫会通过重金属硫蛋白、解毒酶活性的诱导等机制抵御重金属的毒害,从而对低浓度、长期重金属暴露产生生态适应性,甚至提高对其他逆境(如农药等)的耐受性。     

铜矿区超积累Cu植物的研究

1　引　　言土壤重金属污染一直是环境污染问题之一 ,而且土壤中的重金属污染具有严重性、长期性和广泛性的特点[1 ,6] .但常规的一些物理化学方法因费用过高、对土壤性质破坏等一系列问题而难以广泛应用 ,植物修复为重金属污染带来了希望[5,7,9,1 3] .植物修复主要是基于重金属超积累植物 (ｈｙｐｅｒ ａｃｃｕｍｕｌａｔｏｒ)的研究而兴起的 .超积累植物是指地上部分能富集重金属占干重的 1 0 0ｍｇ·ｋｇ-1 (Ｃｕ、Ｐｂ、Ｃｄ)或 1 0 0 0 0ｍｇ·ｋｇ-1 (如Ｚｎ)的一类植物[2～ 4,8] .在过去 2 0年内 ,已报道的超积累植物已有 4 0 0余种 …     

沉水植物对重金属的吸收净化和受害机理研究进展

沉水植物对重金属的积累净化和受害机理研究主要集中在4个方面: (1)沉水植物对重金属(包括放射性物质)的吸收、积累和净化作用; (2)沉水植物对重金属的抗性强弱和机制; (3)沉水植物用于监测水体的重金属污染; (4)沉水植物的重金属胁迫机制, 包括重金属对植物形态和显微结构的损伤, 对植物抗氧化酶系统的影响, 对植物的叶绿素、蛋白质以及光合与呼吸作用等生理生化指标的影响, 植物对重金属的吸附和转运动力学, 以及Zn对Cd毒害的拮抗等。     

重金属胁迫条件下空心莲子草的生长和营养特征分析

空心莲子草是一种常见的水生植物,并能在重金属污染的水体或附近土壤中生长.本研究发现,空心莲子草能富集6种常见的重金属元素,其富集能力为:Zn2+>Mn2+>Pb2+>Cu2+>Cd2+>Cr3+.高浓度(1 mmol/L) Cu2+、Mn2+、Zn2+和Cr3+ 等重金属胁迫处理条件下,空心莲子草的根冠比增加,生物干重、总根长和总根表面积都相应降低.此外,高浓度(1 mmol/L) Pb2+、Cd2+、Cu2+或Zn2+分别胁迫处理条件下,空心莲子草的K+、Ca+和Mg+等元素的含量变化差异显著(P＜0.05).以上研究表明,空心莲子草通过改变体内钾钙镁等重要生长元素营养情况来适应重金属污染的胁迫,有很强的富集重金属元素的能力,进而降低污染、净化水体.空心莲子草对重金属污染的生长响应及体内重要矿物元素营养特性之间的相互关系,可能为重金属污染的水土生物修复提供理论依据.     

金属结合蛋白(肽)与环境重金属生物修复

重金属污染是全球关注的重要环境问题。针对重金属的生物修复技术 ,因其特有的优势 ,越来越受到重视 ,其中一个重要的研究领域是利用金属离子和金属结合蛋白或结合肽之间存在的强亲和能力特性进行的生物修复研究。就金属结合蛋白 (肽 )的种类、结构特点、以及金属结合的作用机理进行了总结 ,同时综述了展示或表达有不同金属结合蛋白或结合肽的微生物和植物对重金属污染进行生物修复的最新研究进展 ,对基于金属结合蛋白 (肽 )的环境重金属生物修复的进一步研究 (如肽库的构建和筛选 ,金属与蛋白 (肽 )的相互作用 )进行了讨论。     

考洲洋重金属污染水平与潜在生态危害综合评价

在等级模型的基础上,利用化学和生态学的方法,在地理信息系统(GIS)的支持下对考洲洋养殖水域表层海水及表层沉积物的重金属污染水平及潜在生态风险进行了综合评价,同时对不同的评价方法进行了分析和比较。结果表明,枯水期整个水域表层海水的重金属污染指数均低于0．5,丰水期更是低于0．2。调查期间湾内海水重金属含量较低,重金属污染不明显。枯水期绝大部分水域表层沉积物重金属的生态风险指数值变化范围为20～70,其高值区出现于湾的西部和西北部水域。表明这些水域的表层沉积物已受到重金属的轻微影响;丰水期整个水域表层沉积物重金属的潜在生态风险指数值均低于20,重金属污染不明显。在生态学方面,枯水期大部分水域的饵料生物水平均处于2～3级水平,其密集分布区位于湾西北部、湾口和吉隆河口附近水域,达4级水平,饵料生物较为丰富。丰水期饵料生物水平的密集分布区位于湾中部和望京洲沿岸水域,饵料生物最丰富,达4～5级水平;其次为湾口,为4级水平;最低则分布于湾的西部和西北部,其饵料生物较低,为1～2级水平。由于重金属污染程度较低,因此水温、盐度和营养盐等环境因子已成为影响湾内生态系统的主要因素。对各种不同评价方法所进行的分析和比较结果表明,采用多指标综合评价方法是描述污染和预测生态效应的一种有效途径。     

苔藓植物对青岛市大气重金属污染的生物监测作用

苔藓植物因具有独特的形态和生理特征, 对空气污染反应十分敏感, 已被广泛用于监测城市或地区的环境质量与变化。通过分析连续2年采自青岛市崂山区的苔藓植物体内重金属含量, 并与崂山土壤重金属含量相比较, 探讨苔藓植物对大气重金属污染物的积累和指示作用。结果表明, 苔藓植物体内重金属含量能够反映空气重金属污染程度和空气质量变化。在崂山广泛分布的毛尖紫萼藓(Grimmia pilifera)对空气中重金属Pb、Zn、Cu和Cd都有着很强的富集能力, 是一种很好的重金属污染指示植物。长叶鳞叶藓(Taxiphyllum taxirameum)、大灰藓(Hypnum plumaeforme)和深绿绢藓(Entodon luridus)在崂山分布较多, 对重金属的积累能力也较强, 可用来监测青岛大气重金属污染。该研究为评价青岛市空气重金属污染状况提供了一个有效的生物监测方法。     

农田土壤重金属污染的陆地生物配体模型研究进展

矿产开采和冶炼、工业"三废"排放等原因导致我国农田土壤重金属污染比较严重。如何科学准确地预测和评价土壤重金属的生物有效性及其生物毒性,是近年来人们关注的热点问题之一。陆地生物配体模型(Terrestrial Biotic Ligand Model,t-BLM)是一种能够预测土壤中重金属生物有效性的机理性模型,模型假设环境中的金属进入到生物体内与一些生物位点结合形成金属-生物配体络合物(BL),当BL达到一定浓度时才会对生物产生毒性,由此判断重金属的生物有效性。本文在综述我国农田土壤重金属污染来源及现状的基础上,讨论了土壤重金属的生物有效性及其生物毒性的研究方法,重点介绍了t-BLM的基本原理,基于植物、土壤动物和微生物为受试生物的t-BLM预测和评价土壤重金属生物有效性及生物毒性的研究进展,提出了t-BLM理论和应用上存在的一些不足。     

Cd、Zn及其交互作用对互花米草中重金属的积累、亚细胞分布及化学形态的影响

通过盆栽试验,研究了Cd、Zn及其交互作用下互花米草中Cd、Zn的含量及积累量,并分析了Cd、Zn在互花米草中的亚细胞分布及化学形态。结果表明：Cd-Zn处理组互花米草地上部及根部Cd含量显著高于Cd处理组;Cd-Zn处理组根部Zn含量显著低于Zn处理组,但地上部差异不显著,说明Zn促进Cd的吸收,Cd抑制Zn的吸收。Cd-Zn处理组互花米草地上部Cd积累量显著高于Cd处理组,但是根部Cd积累量却显著低于Cd处理组;Zn处理组地上部及根部Zn积累量均显著高于对照组及Cd-Zn处理组。Cd单因素胁迫下,Cd主要分布在细胞壁,Cd-Zn交互作用下,Cd在胞液中的分配比例高于其他细胞组分;Zn单因素及Cd-Zn交互作用下,Zn在胞液中的分配比例均较高,总的分配比例呈现以下趋势：胞液>细胞壁>细胞器,说明Zn的添加影响了Cd的亚细胞分布,Cd的出现对Zn在互花米草细胞中的分布影响不明显。Cd和Zn在互花米草叶中主要以氯化钠提取态存在,表明互花米草中Cd和Zn多以果胶酸盐结合态或蛋白质结合态存在。     

镉和锌在皖景天细胞内的分布及化学形态

运用差速离心法和化学试剂逐步提取法,分析了Cd和Zn在皖景天根、茎和叶的亚细胞分布及其化学形态.结果表明:10 μmol·L^-1 Cd处理下,Cd在皖景天细胞内的主要分布位点是其可溶部分;在100 μmol·L^-1 Cd处理下,Cd在根中主要分布在细胞壁、茎中主要分布在细胞壁和可溶部分、叶中超过90%的Cd分布在可溶部分.高Cd浓度处理时,皖景天根、茎和叶的细胞壁中Cd分布比例增加,而可溶部分Cd分布比例相对减少.在1和800 μmol·L^-1 Zn处理条件下,Zn在皖景天根、茎和叶的主要分布位点是可溶部分;高Zn浓度处理时,皖景天叶、茎和根的可溶部分和细胞壁中Zn的分布比例无明显变化.细胞器中Zn和Cd分布都很少.Cd在皖景天根、茎和叶内主要以氯化钠提取态和水提取态存在,Zn在皖景天根、茎和叶内以多种化学形态存在.     

Induction of metallothionein in a human trophoblast cell line by cadmium and zinc

The induction of metallothionein (MT) in a cell line derived from a malignant trophoblastic tumor (JAr cells) was demonstrated using the Cd/heme radioassay following exposure to Cd or Zn. Cd at an optimal concentration of 1 microM produced a 30-fold increase in MT following a 24 hr incubation. Induction by Cd was both time and dose dependent, with a significant increase in MT noted as early as 3 hr, with levels continuing to increase up to 24 hr. Zn was also quite effective in inducing MT synthesis in this cell line. Exposure to 80 microM Zn for 24 hr produced a 70-fold increase in MT. Although Cd was a more potent inducer of MT, exposure to Zn resulted in a greater magnitude of induction. The magnitude of MT induction in JAr cells was much greater than that seen in cultured trophoblasts from term chorion laeve. The degree of induction seen in this cell line makes it an interesting model for the study of MT's role in trophoblast function. MT induction in trophoblasts may reflect a protective mechanism against heavy metal toxicity and/or an integral aspect of normal zinc homeostasis.     

Cellular compartmentation of cadmium and zinc in relation to other elements in the hyperaccumulator Arabidopsis halleri

The cellular compartmentation of elements was analysed in the Zn hyperaccumulator Arabidopsis halleri (L.) O'Kane & Al-Shehbaz (=Cardaminopsis halleri) using energy-dispersive X-ray microanalysis of frozen-hydrated tissues. Quantitative data were obtained using oxygen as an internal standard in the analyses of vacuoles, whereas a peak/background ratio method was used for quantification of elements in pollen and dehydrated trichomes. Arabidopsis halleri was found to hyperaccumulate not only Zn but also Cd in the shoot biomass. While large concentrations of Zn and Cd were found in the leaves and roots, flowers contained very little. In roots grown hydroponically, Zn and Cd accumulated in the cell wall of the rhizodermis (root epidermis), mainly due to precipitation of Zn/Cd phosphates. In leaves, the trichomes had by far the largest concentrations of Zn and Cd. Inside the trichomes there was a striking sub-cellular compartmentation, with almost all the Zn and Cd being accumulated in a narrow ring in the trichome base. This distribution pattern was very different from that for Ca and P. The epidermal cells other than trichomes were very small and contained lower concentrations of Zn and Cd than mesophyll cells. In particular, the concentrations of Cd and Zn in the mesophyll cells increased markedly in response to increasing Zn and Cd concentrations in the nutrient solution. This indicates that the mesophyll cells in the leaves of A. halleri are the major storage site for Zn and Cd, and play an important role in their hyperaccumulation. Received: 4 April 2000 / Accepted: 16 May 2000     

Investigation of heavy metal hyperaccumulation at the cellular level: development and characterization of Thlaspi caerulescens suspension cell lines

The ability of Thlaspi caerulescens, a zinc (Zn)/cadmium (Cd) hyperaccumulator, to accumulate extremely high foliar concentrations of toxic heavy metals requires coordination of uptake, transport, and sequestration to avoid damage to the photosynthetic machinery. The study of these metal hyperaccumulation processes at the cellular level in T. caerulescens has been hampered by the lack of a cellular system that mimics the whole plant, is easily transformable, and competent for longer term studies. Therefore, to better understand the contribution of the cellular physiology and molecular biology to Zn/Cd hyperaccumulation in the intact plant, T. caerulescens suspension cell lines were developed. Differences in cellular metal tolerance and accumulation between the cell lines of T. caerulescens and the related nonhyperaccumulator, Arabidopsis (Arabidopsis thaliana), were examined. A number of Zn/Cd transport-related differences between T. caerulescens and Arabidopsis cell lines were identified that also are seen in the whole plant. T. caerulescens suspension cell lines exhibited: (1) higher growth requirements for Zn; (2) much greater Zn and Cd tolerance; (3) enhanced expression of specific metal transport-related genes; and (4) significant differences in metal fluxes compared with Arabidopsis. One interesting feature exhibited by the T. caerulescens cell lines was that they accumulated less Zn and Cd than the Arabidopsis cell lines, most likely due to a greater metal efflux. This finding suggests that the T. caerulescens suspension cells represent cells of the Zn/Cd transport pathway between the root epidermis and leaf. We also show it is possible to stably transform T. caerulescens suspension cells, which will allow us to alter the expression of candidate hyperaccumulation genes and thus dissect the molecular and physiological processes underlying metal hyperaccumulation in T. caerulescens.     

Subcellular localisation of Cd and Zn in the leaves of a Cd-hyperaccumulating ecotype of<Emphasis Type="Italic"> Thlaspi caerulescens</Emphasis>

Thlaspi caerulescens (Ganges ecotype) is able to accumulate large concentrations of cadmium (Cd) and zinc (Zn) in the leaves without showing any toxicity, suggesting a strong internal detoxification. The distribution of Cd and Zn in the leaves was investigated in the present study. Although the Cd and Zn concentrations in the epidermal tissues were 2-fold higher than those of mesophyll tissues, 65–70% of total leaf Cd and Zn were distributed in the mesophyll tissues, suggesting that mesophyll is a major storage site of the two metals in the leaves. To examine the subcellular localisation of Cd and Zn in mesophyll tissues, protoplasts and vacuoles were isolated from plants exposed to 50 M Cd and Zn hydroponically. Pure protoplasts and vacuoles were obtained based on light-microscopic observation and the activities of marker enzymes of cytosol and vacuoles. Of the total Cd and Zn in the mesophyll tissues, 91% and 77%, respectively, were present in the protoplast, and all Cd and 91% Zn in the protoplast were localised in the vacuoles. Furthermore, about 70% and 86% of total Cd and Zn, respectively, in the leaves were extracted in the cell sap, suggesting that most Cd and Zn in the leaves is present in soluble form. These results indicate that internal detoxification of Cd and Zn in Thlaspi caerulescens leaves is achieved by vacuolar compartmentalisation.     

Cadmium uptake in Escherichia coli K-12.

109Cd2+ uptake by Escherichia coli occurred by means of an active transport system which has a Km of 2.1 microM Cd2+ and a Vmax of 0.83 mumol/min X g (dry weight) in uptake buffer. 109Cd2+ accumulation was both energy dependent and temperature sensitive. The addition of 20 microM Cd2+ or Zn2+ (but not Mn2+) to the cell suspensions preloaded with 109Cd2+ caused the exchange of Cd2+. 109Cd2+ (0.1 microM) uptake by cells was inhibited by the addition of 20 microM Zn2+ but not Mn2+. Zn2+ was a competitive inhibitor of 109Cd2+ uptake with an apparent Ki of 4.6 microM Zn2+. Although Mn2+ did not inhibit 109Cd2+ uptake, the addition of either 20 microM Cd2+ or Zn2+ prevented the uptake of 0.1 microM 54Mn2+, which apparently occurs by a separate transport system. The inhibition of 54Mn2+ accumulation by Cd2+ or Zn2+ did not follow Michaelis-Menten kinetics and had no defined Ki values. Co2+ was a competitive inhibitor of Mn2+ uptake with an apparent Ki of 34 microM Co2+. We were unable to demonstrate an active transport system for 65Zn2+ in E. coli.     

Characteristics of cadmium uptake in two contrasting ecotypes of the hyperaccumulator Thlaspi caerulescens

Uptake of Cd and Zn by intact seedlings of two contrasting ecotypes of the hyperaccumulator Thlaspi caerulescens was characterized using radioactive tracers. Uptake of Cd and Zn at 2 degrees C was assumed to represent mainly apoplastic binding in the roots, whereas the difference in uptake between 22 degrees C and 2 degrees C represented metabolically dependent influx. There was no significant difference between the two ecotypes in the apoplastic binding of Cd or Zn. Metabolically dependent uptake of Cd was 4.5-fold higher in the high Cd-accumulating ecotype, Ganges, than in the low Cd-accumulating ecotype, Prayon. By contrast, there was only a 1.5-fold difference in the Zn uptake between the two ecotypes. For the Ganges ecotype, Cd uptake could be described by Michaelis-Menten kinetics with a V(max) of 143 nmol g(-1) root FW h(-1) and a K(m) of 0.45 microM. Uptake of Cd by the Ganges ecotype was not inhibited by La, Zn, Cu, Co, Mn, Ni or Fe(II), and neither by increasing the Ca concentration. By contrast, addition of La, Zn or Mn, or increasing the Ca concentration in the uptake solution decreased Cd uptake by Prayon. Uptake of Ca was larger in Prayon than in Ganges. The results suggest that Cd uptake by the low Cd-accumulating ecotype (Prayon) may be mediated partly via Ca channels or transporters for Zn and Mn. By contrast, there may exist a highly selective Cd transport system in the root cell membranes of the high Cd-accumulating ecotype (Ganges) of T. caerulescens.     

Glutathione is the antioxidant responsible for resistance to oxidative stress in V79 Chinese hamster fibroblasts rendered resistant to cadmium.

By manipulation of Cd and Zn concentrations in the medium, several phenotypes, differing in the contents of glutathione (GSH) and metallothionein (Mt), were derived from a parental clone of V79 Chinese hamster fibroblast. In some of these phenotypes, resistance to Cd and cross-resistance to oxidative stress was developed. The highest levels of GSH and Mt were found in cells which were rendered resistant to Cd by stepwise increases of Cd and Zn in the cell medium for over 50 passages. Upon removal of Cd/Zn from the medium of these cells or addition of Cd/Zn to the parental cell medium, changes of cellular GSH and Mt levels occurred to different extents. At the same time, changes in the resistance to Cd and H2O2 were observed. Good linear correlations were observed for Mt levels x resistance to Cd and for GSH levels x resistance to H2O2. Poor linear correlations were found for Mt levels x resistance to H2O2 or for GSH levels x resistance to Cd. Moreover, addition of Zn to the medium produced an increase in Mt content without affecting the GSH content. In this case no cross-resistance to oxidative stress was developed. Therefore, Mt which has been shown to be an excellent antioxidant in in vitro experiments, does not seem to play any major role against oxidative stress in Zn and Cd challenged cells. Most of the cross-resistance to oxidative stress in Cd challenged cells seems to be accounted for by the parallel increase in GSH.     

In vitro assessment of target cell specificity in cadmium carcinogenesis: Interactions of cadmium and zinc with isolated interstitial cells of the rat testes

Summary Cadmium (Cd) induces testicular tumors of interstitial cell (IC) origin in rats which can be prevented by zinc (Zn). Zn-induced synthesis of metallothionein (MT), a metal-binding protein with a high affinity for Cd, is thought to account for tolerance to Cd in most tissues by sequenstration of Cd. However, the mechanism of Zn inhibition of Cd-induced carcinogenesis in the testes is unknown. Our studies with ICs obtained by collagenase dispersion of rat testes, indicate the levels of the Cd-binding protein in ICs are unaltered by Zn. This testicular protein also was found to differe from MT in amino acid content and to have a lower affinity for Cd. Thus, MT does not seem to be involved in protection of ICs against Cd carcinogenesis. Altered Cd toxicokinetics as a possible explantation for Zn-induced tolerance was therefore explored. Cd uptake into isolated ICs had passive diffusion and nonpassive (carrier mediated or active transport or both) components. The nonpassive component of Cd accumulation was markedly reduced by addition of Zn in vitro, indicative of competition for uptake at the cellular level. These results indicate that toxicokinetic alterations leading to reduced Cd accumulation may play an important role in Zn induction of tolerance to Cd carcinogenesis in the testes. Paper presented at the 38th Annual Meeting of the Tissue Culture Association in Arlington, Virginia, in May 1987. The session was chaired by Dr. Carlton H. Nadolney, member of the TCA Committee on Toxicity, Carcinogenesis and Mutagenesis Evaluation.