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1.
对重金属和辐射污染的土壤和地下水的微生物修复   总被引：1，自引：0，他引：1  
由重金属和辐射产生的环境污染在世界范围内产生了一系列问题.利用特殊的微生物如金属还原和耐金属细菌对环境中的金属和辐射污染进行处理具有非常好的前景.现场的生物修复的成功应用将对清除污染环境中的重金属和辐射提供潜在方法.最近的研究还关注于了解在微生物群体内重金属和辐射对微生物的作用.生物毯和生物膜是在生物修复中具有代表性的两种微生物群落的机能.金属的种类和价态变化、转移过程以及微生物代谢作用是对金属和辐射生物修复的三种重要的组成部分.结合以上三方面,可以更好的了解自然中的微生物和生物修复过程之间的关系.  相似文献   

2.
The heavy metals at high concentration are generally toxic to the plants for their metabolism and growth; therefore, interactions among metals, rhizosphere microbes and plants have attracted attention because of the biotechnological potential of microorganisms for metal removal directly from contaminated soils or the possible transference of them to the plants. The aim of this study was to compare the relationships between the physiological in vitro characteristics of rhizobacteria isolated from plant metal accumulators and their distribution relating with the heavy metals content in contaminated soils. The results of this study showed that the heavy metals present in the rhizosphere of the plant species analyzed, decrease the microbial biomass and content of heavy metals caused a different distribution of rhizobacteria found. Gram negative rhizobacteria (90 %) and gram positive rhizobacteria (10 %) were isolated; all of them are metal-resistant rhizobacteria and 50 % of the isolated rhizobacteria possess both traits: higher indol acetic acid and siderophore producers. The inoculation with these rhizosphere microorganisms that possess metal-tolerating ability and plant growth promoting activities, can be recommended with a practical importance for both metal-contaminated environment and plant growth promotion.  相似文献   

3.
Methanotrophs: promising bacteria for environmental remediation   总被引：1，自引：1，他引：0  
Methanotrophs are unique and ubiquitous bacteria that utilize methane as a sole source of carbon and energy from the atmosphere. Besides, methanotrophs may also be targeted for bioremediation of diverse type of heavy metals and organic pollutants owing to the presence of broad-spectrum methane monooxygenases enzyme. They are highly specialized group of aerobic bacteria and have a unique capacity for oxidation of certain types of organic pollutants like alkanes, aromatics, halogenated alkenes, etc. Oxidation reactions are initiated by methane monooxygenases enzyme, which can be expressed by methanotrophs in the absence of copper. The present article describes briefly the concerns regarding the unusual reactivity and broad substrate profiles of methane monooxygenases, which indicate many potential applications in bioremediation of heavy metals and toxic organic compounds. Research is needed to develop understanding in plant–methanotrophs interactions that optimize methanotrophs utilization in the field of environmental remediation, while supporting other ecosystem services.  相似文献   

4.
Irrational and rapid global human societal development has culminated to a condition of environmental deterioration. Accidental leakage and deliberate use of organic and inorganic chemicals have contaminated the environment up to the level of ecosystem. Advancements have been made in the field of research on bioremediation of the hazardous contaminants especially in last three decades. Microbial bioremediation has been the most understood biotechnological process of environmental restoration. Bacteria and fungi because of their inherent ability to adapt and grow in extreme environments have been employed for either removal or degradation of the chemical contaminants. Researchers all over the world are getting breakthroughs in finding new bacterial strains having plasmid linked degradation/reduction ability. Molecular biology and genetic engineering helped in crafting the microbes for the desired results on environment. Despite having favorable conditions, microbial remediation largely depends on environmental factors and on the basic biological characters of microbes, especially bacteria being Gram-positive or Gram-negative. Metagenomic studies revealed the importance of microbial ecology as microbes work well in community, i.e., consortia. This review along with several other studies suggests the need of precision during microbial community identification, substrate specificity and the designing of microbes.  相似文献   

5.
土壤修复过程中重金属形态的研究综述   总被引：4，自引：0，他引：4  
重金属污染土壤的修复是现阶段污染土壤治理中的难点之一,在土壤修复过程中对重金属的形态研究已在多个领域中开展,并且在重金属形态及其与生物有效性和毒性等研究领域取得了一定的成果。本文综述了现阶段在污染土壤修复过程中对重金属形态研究的主要领域,分析研究重金属形态的必要性,总结出土壤修复过程中重金属形态方面应当从重金属在土壤与植物中的存在形态入手,研究重金属元素在不同界面间的迁移转化规律,通过阻断重金属元素在污染源、土壤、生物之间的传递链条,以阻止重金属对生物体造成危害,从而为土壤重金属污染的治理修复提供理论基础。  相似文献   

6.
The efficiency of inorganic fertilizers as stimulating agents for the bioremediation of oil-polluted environments can be increased with the addition of selected biostimulating compounds. In this study, the efficacy of different biostimulation treatments in the remediation of diesel-polluted soil in purpose-built microcosms has been evaluated. The treatments involved combinations of inorganic fertilizer with (a) Ivey surfactant, (b) Biorem organic fertilizer and (c) ethanol. Microbial activity was evaluated by monitoring the growth of heterotrophic and degrading bacteria and their dehydrogenase activity and carbon dioxide production. Hydrocarbon degradation was monitored by gas chromatography/mass spectrometry. The results showed that all treatments enhanced microbial activity in comparison with natural attenuation and also that the combined treatments generally enhanced hydrocarbon biodegradation in comparison to both natural attenuation and the single inorganic fertilizer treatment. The inorganic fertilizer plus Ivey? surfactant was the most efficient treatment in terms of Total Petroleum Hydrocarbon and light and heavy n-alkanes, showing an index of degradation of 1.4 and 1.3, respectively. Furthermore, biodegradation of heavy and branched n-alkanes was higher in microcosms treated with inorganic fertilizer plus ethanol (Index of degradation values of 1.6 and 1.5, respectively) indicating that combined treatments can be very effective in restoration of contaminated soil.  相似文献   

7.
One of the most cost-effective in situ technologies for soil and groundwater (i.e., aquifer) remediation is electrokinetic remediation. In electrokinetic remediation, electromigration due to electric field is combined with hydromigration due to hydraulic flow by purge water to remove pollutants from aquifers through the pore water. This study aims at investigating theoretically the role of electromigration (as active movement) of pollutants and the role of hydromigration (as passive movement) of pollutants in electrokinetic remediation, and making it clear that the control variables for electrokinetic remediation are the applied voltage and the hydraulic flow rate. These aims are pursued by construction of a mathematical model based on physico-chemical considerations and by model simulations of the electrokinetic remediation applied to the virtual aquifer polluted by heavy metals of copper sulfate. According to numerical simulations with the model: (1) heavy metal (nonanionic copper) is removed from the upstream anode region and accumulated in the downstream cathode region; (2) to carry away the heavy metal outside the aquifer (global removal), hydromigration by purge water flow is essential; and (3) electromigration contributes mainly to the redistribution of heavy metals within the aquifer (local removal and local accumulation).  相似文献   

8.
土壤污染日益严重,其中作为土壤污染类型之一的放射性核素污染已引起广泛关注。土壤中的部分微生物可以矿化 固结重金属离子,从而达到去除重金属离子的目的。本文实验对从土壤中分离的1株碳酸盐矿化菌的特性及其对Sr2+的矿化 结果进行研究,发现该菌对1.0g/L和0.5g/L模拟核素Sr2+的去除率可达98%和99%。扫描电子显微镜（SEM）、能谱分析 （EDS）、X射线衍射（XRD） 、傅里叶变换红外光谱（FTIR）等结果显示,矿化产物为碳酸锶。可见,利用碳酸盐矿化菌 治理土壤中放射性核素Sr2+污染具有可行性,该方法将会有一定应用前景。  相似文献   

9.
曾远  罗立强 《岩矿测试》2017,36(3):209-221
随着经济的发展,矿产资源的开采和利用程度越来越高,一方面发现有地表露头矿床的几率越来越小,另一方面其造成的重金属污染严重危害环境和人类健康。自然界中的微生物与扩散到环境中的重金属会产生相互作用,具有这种特异性的细菌既可应用于指示隐伏金属矿床,亦可应用于重金属污染生物修复。本文从特异性微生物与重金属相互作用微观机制、微生物找矿、重金属污染土壤的微生物修复三个方面,对其研究现状和进展进行了评述,重点对特异性微生物与重金属离子发生的吸附、累积与转化过程,微生物改变重金属元素分布、赋存状态和毒性作用机理,蜡样芽孢杆菌(Bacillus cereus)与金的作用机制及其在寻找隐伏金矿的应用潜力,特异性微生物通过代谢产物吸附去除土壤中重金属元素及其辅助植物修复重金属污染等方面进行了介绍和阐述。  相似文献   

10.
The present study deals with the characterization of effluent released from sponge iron industries and distribution of heavy metals in soil and macrophytes near to effluent discharge channel. Apart from this, accumulation of heavy metals in nearby soil and vegetation system irrigated with effluent-contaminated water is also the subject of this study. Physico-chemical analysis of effluent reveals that the concentration of total suspended solids (TSS), total hardness (TH), iron (Fe2+), and oil and grease are greater than the IS (1981) norms for discharge of water into inland water body. The soil along the sides of the effluent channel also shows higher concentration of heavy metals than the background soil. The enrichment of the heavy metals are in the order of Chromium (Cr) > Iron (Fe) > Manganese (Mn) > Zinc (Zn) > Copper (Cu) > Cadmium (Cd). Macrophytes growing along the sides of the effluent channel also show significant accumulation of heavy metals almost in the same order as accumulated in soil. Higher uptake of heavy metals by these varieties reveals that these species can be used for future phytoremediation. The effluent as well as contaminated water is extensively used for irrigation for growing vegetables like tomato (Lycopersicon esculatum) in the surrounding areas. Heavy metal accumulation in this agricultural soil are in the sequence of Cr > Fe > Mn > Zn > Cu > Cd. More or less similar type of accumulation pattern are also found in tomato plants except Fe and Zn exceeding Cr and Mn. Transfer Factor of heavy metals from soil to tomato plants (TFS) shows average value of <1, suggesting less uptake of heavy metals from soil. Among the plant parts studied, fruit shows least accumulation. Although tomato plants show some phenotypic changes, the survival of tomato plants as well as least accumulation of metals in fruit reveals their tolerance to heavy metals. Therefore it may be suggested that this plant can be grown successfully in the heavy metal contaminated soil. Further research work on in situ toxicity test will be necessary in order to identify the most resistive variety on this particular type of contaminated site.  相似文献   

11.
为了研究一种高效的多种重金属污染土壤修复剂,本文采用了一种具有OH-缓释功能的改性Mg（OH）2,通过重金属污染土壤稳定化修复实验,探讨了改性Mg（OH）2对污染土壤中多种重金属（Pb、Cd、Cu、Zn）的稳定效率及对多种重金属形态分布的影响。结果表明,投加改性Mg（OH）2对土壤中多种重金属均有稳定作用,对Pb、Cd、Cu、Zn的稳定效率分别为72.42%、34.53%、87.64%和97.65%,且改性Mg（OH）2的投加使重金属交换态质量明显减少、残渣态质量增加,进一步提高了重金属的稳定性,降低了重金属生物有效性;另外,改性Mg（OH）2具有OH-缓释性,可使土壤长期保持一定的碱性,是一种经济有效的土壤修复剂。  相似文献   

12.
Chlorinated hydrocarbons can cause serious environmental and human health problems as a result of their bioaccumulation, persistence and toxicity. Improper disposal practices or accidental spills of these compounds have made them common contaminants of soil and groundwater. Bioremediation is a promising technology for remediation of sites contaminated with chlorinated hydrocarbons. However, sites co-contaminated with heavy metal pollutants can be a problem since heavy metals can adversely affect potentially important biodegradation processes of the microorganisms. These effects include extended acclimation periods, reduced biodegradation rates, and failure of target compound biodegradation. Remediation of sites co-contaminated with chlorinated organic compounds and toxic metals is challenging, as the two components often must be treated differently. Recent approaches to increasing biodegradation of organic compounds in the presence of heavy metals include the use of dual bioaugmentation; involving the utilization of heavy metal-resistant bacteria in conjunction with an organic-degrading bacterium. The use of zero-valent irons as a novel reductant, cyclodextrin as a complexing agent, renewable agricultural biosorbents as adsorbents, biosurfactants that act as chelators of the co-contaminants and phytoremediation approaches that utilize plants for the remediation of organic and inorganic compounds have also been reported. This review provides an overview of the problems associated with co-contamination of sites with chlorinated organics and heavy metals, the current strategies being employed to remediate such sites and the challenges involved.  相似文献   

13.
从安徽铜陵杨山冲尾矿库采集表层尾矿样品,通过砷富集培养,从3份样品中筛选得到3株具有较强As(Ⅲ) 抗性的细菌 WK-21、WK-31 和 WK-32,用不同 NaAsO2 浓度的 LB 培养基对菌株进行砷抗性检测,结果这3株菌分别能耐受32、56和50 mmol/L的As(Ⅲ),具有较高的耐砷性.对这3株菌进行不同梯度浓度 As(Ⅲ) 环境中的生长规律研究,结果表明砷在低浓度时对细菌生长有轻微促进作用或者几乎没影响,但随着砷浓度增大,抑制作用明显增强.根据对这3株菌进行形态观察、生理生化鉴定以及16S rDNA序列比对分析,鉴定出这3株菌分别属于Arthrobacter sp.、Rhodococcus equi和Paenibacillus sp.菌属.由于这些菌株分离于尾矿库的尾矿堆中,因此,本文研究结果为进一步研究尾矿库金属污染的微生物修复及微生物抗金属机制提供了材料.  相似文献   

14.
地浸采铀技术已成为世界采铀的主流工艺,采区退役后地下水环境修复亦为人们所关注的热点。文章简要介绍了碱法、中性和酸法三种典型地浸采铀技术的特点,系统分析了地浸采铀对地下水环境的影响,并以酸法地浸铀矿山地下水环境修复技术为例,重点介绍了物理化学修复技术和生物修复技术及其原理与应用,归纳总结了其优缺点,并对未来的研究方向进行了展望。指出下一步应加强在酸性与氧化环境中能使铀固定并长期稳定的新技术,高活性、强适应性修复菌群的选育、驯化技术,地下水异位-原位协同生物修复技术,以及放射性核素及重金属在铀矿地浸地下水环境中的吸附-解吸、氧化-还原、溶解-沉淀等行为与机理及其主控因素等方面的研究。  相似文献   

15.
研究了固定配比的钠化膨润土与土壤在不同pH条件下对重金属离子的吸附效果。钠化膨润土与污染土壤按质量比1∶10和1∶20的比例混合,用碳酸氢铵-二乙三胺五乙酸(AB-DTPA)法提取土壤中有效态重金属。结果表明,在钠化膨润土与土壤质量比为1∶20的条件下,取得了最佳的修复效果;在pH=9.14时该混合土壤对重金属的总体吸附效果最佳。在实际土壤修复中,针对不同重金属污染,应灵活调整修复材料与污染土壤的配比和土壤的pH条件。  相似文献   

16.
Heavy metals are known to pose a potential threat to terrestrial and aquatic flora and fauna. Due to increasing human influence, heavy metal concentrations are rising in many mangrove ecosystems. Therefore, an assessment of heavy metal (Cd, Cr, Cu, Ni, Pb, Fe, Mn, and Zn) concentrations was conducted within the bulk soil and rhizosphere soil of Avicennia marina at the Pichavaram Mangrove Forest in India. The rhizosphere soil showed higher concentrations of metals than the bulk soil. Compared to the bulk soil, the metals Cd, Fe, Mn, and Zn were 6.0–16.7% higher, whereas Cr, Cu, Ni, and Pb were 1.7–2.8% higher concentration. Among the three selected sampling sites (dense mangrove forest, estuarine region, and sea region), the sea region had the highest concentration of all heavy metals except Zn. The trend of the mean metal concentration was Fe > Mn > Cr > Ni > Cu > Pb > Zn > Cd. Heavy metals concentrations elevated by the 2004 tsunami were persistent even after 4 years, due to sedimentary soil processes, the rhizosphere effect of mangroves, and anthropogenic deposition. Analysis of the heavy metal-resistant bacteria showed highest bacterial count for Cr-resistant bacteria and rhizosphere soil. The maximum level of heavy metal-resistant bacteria was observed at the site with the highest heavy metal contamination. The heavy metal-resistant bacteria can be used as indicator of heavy metal pollution and furthermore in bioremediation.  相似文献   

17.
Pozzolanic-based stabilization/solidification (S/S) is an effective, yet economic remediation technology to immobilize heavy metals in contaminated soils and sludges. In the present study, fly ash waste materials were used along with quicklime (CaO) to immobilize lead, trivalent and hexavalent chromium present in artificially contaminated clayey sand soils. The degree of heavy metal immobilization was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) as well as controlled extraction experiments. These leaching test results along with X-ray diffraction (XRD), scanning electron microscope and energy dispersive X-ray (SEM–EDX) analyses were also implemented to elucidate the mechanisms responsible for immobilization of the heavy metals under study. Finally, the reusability of the stabilized waste forms in construction applications was also investigated by performing unconfined compressive strength and swell tests. The experimental results suggest that the controlling mechanism for both lead and hexavalent chromium immobilization is surface adsorption, whereas for trivalent chromium it is hydroxide precipitation. Addition of quicklime and fly ash to the contaminated soils effectively reduced heavy metal leachability well below the nonhazardous regulatory limits. Overall, fly ash addition increases the immobilization pH region for all heavy metals tested, and significantly improves the stress-strain properties of the treated solids, thus allowing their reuse as readily available construction materials. The only potential problem associated with this quicklime–fly ash treatment is the excessive formation of the pozzolanic product ettringite in the presence of sulfates. Ettringite, when brought in contact with water, may cause significant swelling and subsequent deterioration of the stabilized matrix. Addition of minimum amounts of barium hydroxide was shown to effectively eliminate ettringite formation. Overall, due to the presence of very high levels of heavy metal contamination along with sulfates in the solid matrices under study, the results presented herein can be applied to the management of incinerator and coal fly ash, boiler slag and flue gas desulfurization wastes.  相似文献   

18.
生物炭修复重金属污染土研究进展   总被引：4，自引：0，他引：4  
随着城市化进程的加快及工业生产的迅速发展,土壤重金属污染日益加剧,对生态环境造成严重的危害。生物炭是缺氧或限氧条件下加热生物质制得的高度芳香化富含碳的固态物质,其在重金属污染土修复方面具有显著效果,受到广泛关注。基于近些年来国内外围绕生物炭修复重金属污染土所取得的研究成果,分别从生物炭的制备及性质、修复效果及其影响因素、修复机理等方面总结了该领域的研究现状及进展,取得如下主要认识:（1）生物炭具有价格低廉,修复效率高,改良土壤、环境友好等优势;（2）生物炭的理化性质主要受原材料和热解温度的影响,采用活化、磁化、氧化和消化等方法能改善生物炭的性质,提高修复效率;（3）生物炭对土壤中重金属迁移性和生物有效性的影响包括两个方面:固定重金属减少生物有效性或者迁移重金属增加生物有效性,后者可通过改性方法来降低重金属的迁移性和生物有效性;（4）生物炭对土体的固化效果一般,但可与其他固化材料共同使用,以改善土体的力学性质;（5）生物炭修复机理固定重金属的效果为:沉淀作用>络合作用>静电作用,离子交换>物理吸附。最后,针对该领域的研究现状,提出了未来的研究重点和方向,主要包括:建立划分生物炭的统一标准;探讨生物炭对多种重金属共同污染的修复效率;阐明生物炭吸附重金属的机理及其贡献率;扩大研究尺度;开展基于生物炭的固化试验及力学性质研究。  相似文献   

19.
将碳酸氢铵-二乙三胺五乙酸(AB-DTPA)提取重金属生物有效态的方法应用于重金属污染土壤修复的模拟试验中,该土壤的污染元素主要是铜、锌和镉,试验所用修复材料是钠化膨润土。研究表明,AB-DTPA提取法具有很好的稳定性,而且能准确指示铜、锌、镉元素在土壤中的有效态含量,同时AB-DTPA对土壤中铜、锌、镉元素的提取率也适用于模拟试验中修复效果的平行对比。AB-DTPA提取法在重金属污染土壤修复模拟试验中的应用是可行的。  相似文献   

20.
Emerging environmental issues related to heavy metal contamination in rice draw great concern about the soil quality of paddy farming lands irrigated with groundwater. Investigating the functioning of soil microorganisms exposed to heavy metal contamination is imperative for agricultural soil manipulations. The current study accentuates the influence of heavy metals on microbial activity and community composition in arable soil of West Bengal State of India. The result revealed that the fertility indicators (activity of all soil enzymes) and growth-limiting factors (soil N and P) were negatively correlated with the heavy metal stress except the soil total organic content which demonstrated significant positive correlation with the heavy metals. In case of functional diversity of soil, all the considered diversity indices exhibited no specific pattern along with the availability of heavy metals. Further, despite the heavy metal contamination, we observed a very complex and indifferent pattern of bacterial community composition along the heavy metal contamination sites. Overall, we found that γ-Proteobacteria had been the most abundant bacterial community followed by Actinobacteria, Firmicutes, β-Proteobacteria and α-Proteobacteria. Commemorating all the results, we can infer that arsenic and other heavy metal contamination is deteriorating the soil quality and hence warrants immediate attention of concerned soil scientist and agronomists.  相似文献   

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