重金属污染土壤提高植物提取修复功效的探讨

随着对重金属超积累植物研究的加深，用植物提取修复技术来改良重金属污染的土壤已逐步进入实用阶段。本文所探讨的提高此技术功效的方法基于两个方面：提高土壤溶液中重金属的浓度，促进植物对重金属的吸收，根据已了解的超积的生理机制可能采取的一些措施。     

植物修复及重金属在植物体内形态分析综述

植物修复是重金属污染土壤治理的重要方法,因其具有高效、经济及生态协调性等优势而广受关注。当前相关研究主要包括超积累植物体内重金属的迁移转化与形态分析方法,土壤修复后植物的减量化、无害化和资源化利用等方面。实验研究及修复工程中存在的问题主要体现为:(1)基础研究方面,目前对植物超积累重金属的分子机制、调控原理等方面的研究不够完善;(2)应用技术方面,修复植物的规模化种植、适用的栽培技术、收获物安全处置及资源化利用方面仍是植物修复技术发展的瓶颈。因此,目前需要深入研究超积累植物吸收、运输和积累重金属的生理机制,利于植物生长的农业措施以及用于修复的植物收获后的相应处理技术。同时,应结合重金属在植物体内的形态,对修复后的植物进行合理的减量化、无害化、资源化处理,以便于更加科学合理地选择土壤重金属修复植物,大规模推广植物修复技术的应用。     

土壤重金属污染的植物修复研究进展

详细阐述了植物修复的生理学、分子生物学机制，包括超积累植物对根际土壤中重金属的活化，超量积累植物对土壤重金属吸收及其解毒机理，并就该领域今后的研究方向和存在的问题作了探讨。     

有机肥料联合东南景天修复重金属污染土壤的研究

将两种有机肥料黄腐酸钾和紫云英(Astragalus sinensis)分别与重金属超积累植物东南景天(Sedum alfredii)联用修复重金属污染土壤,研究有机肥料对污染土壤重金属生物有效性、形态以及东南景天重金属积累量的影响。结果显示,修复0～4个月,施加有机肥料对土壤重金属生物有效性均有一定的促进作用;而修复4～8个月,土壤重金属向可氧化态和残渣态转化,生物有效性受到抑制。从东南景天地上部重金属积累量看,修复0～4个月,施加0.3%(质量分数)黄腐酸钾促进东南景天对锌、镉的吸收积累,锌、镉积累量分别比对照提高了280.37%、265.44%;而修复4～8个月,东南景天地上部重金属积累量相较对照均下降。由此可见,提升重金属污染土壤的植物修复效果,还需考虑修复周期的影响。     

人工湿地植物对重金属铅的抗性

随着含铅废水污染引起的生态安全问题日益加重,以及处理要求的日益严格,含铅废水的处理已成为目前研究和工程实践的重点。由于植物修复技术操作管理方便,成本低廉,处理效率高和选择性强等优点,植物修复已成为处理含铅废水的较有潜力的和行之有效的优化技术。实验参照水体重金属污染现状,模拟设置不同铅浓度的水体,通过盆栽水培实验及实验室分析测试,分别研究了重金属铅对芦苇、香蒲、鸭跖草这3种植物生长的影响、分析各种植物对铅的抗性的表现及重金属在植物体内的积累和分布,为人工湿地植物的选择提供科学依据。     

农用地重金属污染植物提取修复技术研究进展

农用地重金属污染具有污染范围广、风险筛选值和风险管制值相对较低等特点,使常规土壤修复技术如客土法、化学淋洗法、固化稳定化等的应用受到限制,植物提取技术是修复农用地重金属污染的有效手段。介绍了富集植物种类、超富集植物的评判依据、富集植物对重金属提取机制,重点分析了植物提取技术在农用地修复应用中的效果、影响因素、存在的问题及强化措施,最后对植物提取技术修复重金属污染农用地的未来发展方向进行了展望。     

兰坪铅锌矿区不同污染梯度下优势植物的重金属累积特征

对兰坪铅锌矿区污染程度不同的3个样地(云南松林、魁蒿群落和马桑灌丛)进行植被调查,选择其中9种共有的自然生长的优势草本植物为研究对象,测定了土壤及植物体的重金属含量。结果显示,3个样地土壤Cu、Cd、Pb和Zn等4种重金属含量均表现为马桑灌丛>魁蒿群落>云南松林;植物体内重金属积累呈现出随着土壤污染程度增加而增加的趋势;所选择的9种植物均不符合超富集植物的标准,依据不同的耐性机制将9种植物分为3类,野棉花能较强吸收土壤中重金属,并转移到地上部分,属于富集型植物;西南金丝梅、倒提壶、长籽柳叶菜、魁蒿、翻白叶和四脉金茅吸收的重金属主要积累在根部,属于根部囤积型植物;尼泊尔蓼和中华山蓼体内重金属含量较低,属于规避型植物。讨论了利用这些植物进行矿山治理。     

4种茄科植物对矿区污染土壤重金属的吸收和富集

采集了湖南及江苏8个矿区或冶炼厂周边4种茄科(Solanaceae)植物及其根际土壤,分析了植物及土壤样品中Cd、Cu、Pb、Mn和Zn 5种重金属浓度.结果表明:番茄(Lycopersicon esculentum)对5种重金属可能有着较强的耐性,但不具有超积累的潜力;刺天茄(Solanum indicum)对Mn、...     

氮磷钾和乙二胺四乙酸对镉污染三叶鬼针草的吸收特征研究

超富集植物的筛选是植物修复重金属污染土壤技术的核心内容.采用盆栽试验的方法,研究了Cd胁迫下添加营养元素N、P、K和螯合剂乙二胺四乙酸(EDTA)对三叶鬼针草(Bidens pilosa L.)的生长反应和生理生化特性以及对Cd的吸收积累特征.盆栽试验结果显示,在Cd为10 mg/kg时,添加营养元素N、P、K和EDT...     

某铅锌矿坑口周围具有重金属超积累特征植物的研究

针对目前植物修复中Cd-Pb-Cu-Zn复合污染的超富集植物缺乏研究,采用野外采样系统分析方法,对青城子铅锌矿各主要坑口周围17科31种杂草植物进行其积累特性的初步研究。结果表明,全叶马兰(Kalimeris integrifolia)、蒲公英(Taraxacum mongolicum)和鬼针草(Bidens bipinnata)3种植物地上部对Cd的富集系数均>1,且地上部Cd含量大于根部Cd含量,具备了重金属超富集植物的基本特征,进一步研究的价值很大。以杂草为对象筛选超富集植物很可能获得较大突破。     

Contributions of heavy metals from municipal runoff to the sediments of Lake Pontchartrain, Louisiana

A study was conducted to determine the distribution and sources of heavy metal pollutants in the sediments of Lake Pontchartrain. Sediment samples were collected from the northern and southern shorelines and analyzed for heavy metals by atomic absorption spectrometry. The heavy metals of interest were barium, copper, nickel, lead, and zinc. The concentrations of these metals indicate that the principal source of heavy metal pollution is associated with urban stormwater runoff and municipal discharges.     

Sequential extraction of heavy metals in river sediments of an abandoned pyrite mining area: pollution detection and affinity series

In this paper heavy metal pollution at an abandoned Italian pyrite mine has been investigated by comparing total concentrations and speciation of heavy metals (Fe, Cu, Mn, Zn, Pb and As) in a red mud sample and a river sediment. Acid digestions show that all the investigated heavy metals present larger concentrations in the sediment than in the tailing. A modified Tessier's procedure has been used to discriminate heavy metal bound to organic fraction from those originally present in the mineral sulphide matrix and to detect a possible trend of metal mobilisation from red mud to river sediment. Sequential extractions on bulk and size fractionated samples denote that sediment samples present larger percent concentrations of the investigated heavy metals in the first extractive steps (I-IV) especially in lower dimension size fractionated samples suggesting that heavy metals in the sediment are significantly bound by superficial adsorption mechanisms.     

土壤重金属的植物污染化学研究进展

针对中国土壤重金属污染加剧的趋势,为改善土壤环境质量和保障农产品安全,提出了土壤重金属的植物污染化学研究领域.结合多年的研究工作,从土壤重金属的植物根际化学行为、土壤重金属的植物吸收与解毒机制和重金属污染土壤的植物-微生物交互作用等方面简要阐述了土壤-植物系统中重金属的分布、存在形态、迁移转化、累积及生物学效应和控制规律的研究进展,并对将来的植物污染化学理论研究提出了展望.     

Heavy metals in plants and phytoremediation

GOAL, SCOPE AND BACKGROUND: In some cases, soil, water and food are heavily polluted by heavy metals in China. To use plants to remediate heavy metal pollution would be an effective technique in pollution control. The accumulation of heavy metals in plants and the role of plants in removing pollutants should be understood in order to implement phytoremediation, which makes use of plants to extract, transfer and stabilize heavy metals from soil and water. METHODS: The information has been compiled from Chinese publications stemming mostly from the last decade, to show the research results on heavy metals in plants and the role of plants in controlling heavy metal pollution, and to provide a general outlook of phytoremediation in China. Related references from scientific journals and university journals are searched and summarized in sections concerning the accumulation of heavy metals in plants, plants for heavy metal purification and phytoremediation techniques. RESULTS AND DISCUSSION: Plants can take up heavy metals by their roots, or even via their stems and leaves, and accumulate them in their organs. Plants take up elements selectively. Accumulation and distribution of heavy metals in the plant depends on the plant species, element species, chemical and bioavailiability, redox, pH, cation exchange capacity, dissolved oxygen, temperature and secretion of roots. Plants are employed in the decontamination of heavy metals from polluted water and have demonstrated high performances in treating mineral tailing water and industrial effluents. The purification capacity of heavy metals by plants are affected by several factors, such as the concentration of the heavy metals, species of elements, plant species, exposure duration, temperature and pH. CONCLUSIONS: Phytoremediation, which makes use of vegetation to remove, detoxify, or stabilize persistent pollutants, is a green and environmentally-friendly tool for cleaning polluted soil and water. The advantage of high biomass productive and easy disposal makes plants most useful to remediate heavy metals on site. RECOMMENDATIONS AND OUTLOOK: Based on knowledge of the heavy metal accumulation in plants, it is possible to select those species of crops and pasturage herbs, which accumulate fewer heavy metals, for food cultivation and fodder for animals; and to select those hyperaccumulation species for extracting heavy metals from soil and water. Studies on the mechanisms and application of hyperaccumulation are necessary in China for developing phytoremediation.     

Bioleaching of heavy metals from sediment: significance of pH

Bioleaching process, which causes acidification and solubilization of heavy metals, is one of the promising methods for removing heavy metals from contaminated sediments. The solubilization of heavy metals from contaminated sediments is governed by the sediment pH. In the present study, the significance of pH in bioleaching of heavy metals from contaminated sediment was evaluated at different solid contents of sediments in a bench-scale reactor. Results showed that a temporal change of pH in the bioleaching process was effected by the buffering capacity of the sediment particulates. The variations of pH in this bioleaching process were calculated by a modified logistic model. It was observed that solubilization of heavy metals from sediments is highly pH-dependent. In addition, a non-linear equation for metal solubilization relating pH value in the bioleaching process was established. This allows an easier and faster estimate of metal solubilization by measuring pH in the bioleaching process.     

Effects of Heavy metals on plants and resistance mechanisms

GOAL, SCOPE AND BACKGROUND: As one of the consequences of heavy metal pollution in soil, water and air, plants are contaminated by heavy metals in some parts of China. To understand the effects of heavy metals upon plants and the resistance mechanisms, would make it possible to use plants for cleaning and remediating heavy metal-polluted sites. METHODS: The research results on the effects of heavy metals on plants and resistant mechanisms are compiled from Chinese publications from scientific journals and university journals, mostly published during the last decade. RESULTS AND DISCUSSION: Effects of heavy metals on plants result in growth inhibition, structure damage, a decline of physiological and biochemical activities as well as of the function of plants. The effects and bioavailability of heavy metals depend on many factors, such as environmental conditions, pH, species of element, organic substances of the media and fertilization, plant species. But, there are also studies on plant resistance mechanisms to protect plants against the toxic effects of heavy metals such as combining heavy metals by proteins and expressing of detoxifying enzyme and nucleic acid, these mechanisms are integrated to protect the plants against injury by heavy metals. CONCLUSIONS: There are two aspects on the interaction of plants and heavy metals. On one hand, heavy metals show negative effects on plants. On the other hand, plants have their own resistance mechanisms against toxic effects and for detoxifying heavy metal pollution. RECOMMENDATIONS AND OUTLOOK: To study the effects of heavy metals on plants and mechanisms of resistance, one must select crop cultivars and/or plants for removing heavy metals from soil and water. More highly resistant plants can be selected especially for a remediation of the pollution site. The molecular mechanisms of resistance of plants to heavy metals should be studied further to develop the actual resistance of these plants to heavy metals. Understanding the bioavailability of heavy metals is advantageous for plant cultivation and phytoremediation. Decrease in the bioavailability to farmlands would reduce the accumulation of heavy metals in food. Alternatively, one could increase the bioavailability of plants to extract more heavy metals.     

不同土壤重金属复合污染的有效态离子冲量表征

选择红壤、黄棕壤和潮土为对象，依据中国土壤环境质量二级和三级标准确定土壤重金属铜、锌、镉的污染浓度，通过生物盆裁试验研究在重金属Cu、Zn、Cd复合污染条件下牧草（黑麦草、紫花苜蓿）体内重金属含量和土壤中重金属有效态含量的相关性，结果表明，在3种不同性质的污染土壤上，牧草体内重金属的离子冲量与其对应土壤中重金属有效态的离子冲量之间均存在明显的相关性。校正土壤pH、牧草品种等因素后，土壤有效态离子冲量可以有效表征不同土壤-牧草系统的重金属复合污染。     

Further investigation of the heavy metal content of the teeth of the bank vole as an exposure indicator of environmental pollution in Poland

The content of heavy metals in mineralised dental tissues is an indicator of the exposure of their mineral phase to heavy metals during the time of tooth development and dental tissue formation. Therefore, teeth have been used as bio-indicators which accurately reflect the environmental or dietary exposure of animals and humans to heavy metals. This study follows from the earlier work in which it was demonstrated that the teeth from bank voles inhabiting various environmentally polluted and non-polluted forests in Southern Poland were reliable indicators of exposure to heavy metals. Using analytical techniques employed in the earlier study heavy metal concentrations were obtained in the teeth of bank voles trapped in 1998-2000 to determine if efforts to clean up the environment could be detected in changes in heavy metal concentrations in the teeth. The results show that these efforts are reflected in lower concentrations of heavy metals in the teeth but that cross border contamination remains a problem.     

Effects of heavy metals on population growth and metallothionein gene expression in the mosquito Culex quinquefasciatus, from Calcutta, India

Major water bodies in and around the city of Calcutta (India) receive heavy metal contaminated effluents from industries, households, and vehicular traffic through sewage or drainage. We quantified concentrations of Cu, Zn, and Cd from three water bodies at Kalighat, Tangra, and VIP Road, respectively. The concentrations of these heavy metals were significantly greater in the summer than in monsoon when heavy downpours resulted in reduced metal concentrations. Concentrations of metals in the mosquito Culex quinquefasciatus also reflected such seasonal fluctuations. Hatchability and survivorship of C. quinquefasciatus significantly differed among the sites and were reduced significantly from the control. Exposure to heavy metals also induced MT-gene expression in C. quinquefasciatus, likely helping them to survive in the water bodies stressed with heavy metals. MT-gene activity demonstrated significant variation among sites and seasons with the highest activity in the summer in the VIP Road population. This study suggests that C. quinquefasciatus could be used as an ecological indicator of heavy metal pollution by monitoring its MT-gene expression.     

土壤重金属复合污染及其化学钝化修复技术研究进展

土壤重金属污染往往是2种或2种以上的多种重金属并存的复合污染。与单一污染相比，重金属复合污染中元素或化合物之间存在相互作用以及对生态效应的综合影响，对其污染土壤的修复具有挑战性。目前，土壤重金属污染的修复主要集中在单一元素上，而对土壤多种重金属并存的复合污染的同时修复研究较少。化学钝化修复是基于向土壤中添加稳定化剂，通...