矿区重金属污染土壤修复技术的研究现状和展望

矿区土壤重金属污染是当今世界面临的主要环境问题之一,其污染修复一直是环境科学领域研究的重要领域之一。对矿区土壤重金属污染的修复方法,包括物理化学技术、植物修复技术、动物修复技术的机理、优缺点以及实用性进行了综述,并对矿区土壤修复的研究进行了展望。     

农用地重金属污染现状及修复方法

土壤是农业生产的基础,随着社会的进步和经济的高速发展,越来越多的污染物排入土壤,其中重金属所占的比例逐渐增大,成为土壤治理的主要对象。农用地重金属污染不仅会导致作物产量降低,而且重金属会随着食物链在人体内积累,对人体产生极大的危害,因此重金属污染修复迫在眉睫。文章综述了农用地重金属污染现状、来源以及各种修复技术,分析了不同修复技术的优势及不足,为运用联合修复技术控制农用地重金属污染提供一定的借鉴与思路。     

污染土壤电动修复技术研究进展

电动修复是一种新兴的原位土壤修复技术,主要用于有机及重金属污染土壤/场地的修复.本文作者介绍了电动修复污染土壤的技术原理;探讨了电动技术与Fenton技术、表面活性剂/助溶剂、超声波技术、微生物技术及渗透性反应屏障技术的联合应用;总结了土壤电动修复中,土壤pH不均衡及有机污染修复效率较低的问题.确定了电动技术与多种技术的联用为土壤修复的研究和应用趋向.     

双金属复合氢氧化物在重金属污染土壤/水修复方面的研究进展

重金属污染土壤/水形势严峻,修复工作迫在眉睫.开发高效率、低成本、易操作的重金属污染土壤/水修复材料及技术极具重要现实意义.类水滑石(又称双金属复合氢氧化物, LDHs)是一类典型的无机层状结构材料.独特的组成及结构特点使得LDHs在重金属离子去除领域表现出良好的应用前景,特别是在原位修复重金属污染土壤领域已实现应用,表现出超稳矿化性能,修复效果显著,同时为重金属污染水修复工作提供了新的思路.本文总结了近年来LDHs作为修复材料在重金属污染土壤/水修复方面的工作,阐述了LDHs材料的结构与性能间的内在关联和作用机理,并对该材料在去除重金属离子方面存在的问题及应用前景进行了汇总和展望.     

重金属污染土壤植物修复的强化措施研究进展

植物修复是一种有着巨大市场潜力的治理重金属污染土壤的技术,由于影响植物修复效率的因素较多,至今实际应用还很少。针对目前植物修复技术的不足,主要从植物本身的性能、重金属的生物有效性以及农艺管理措施等三方面,综述了近年来国内外有关植物修复强化措施的研究进展,并展望了今后该领域的研究方向。     

电动修复土壤中重金属污染的改良方法

介绍了治理土壤重金属污染的电动修复技术的一些进展,包括:通过控制电解过程中的极化、土壤pH值、控制土壤温度来对电动修复技术方法进行改良。     

重金属污染场地物理化学修复技术研究与工程应用进展

结合我国国情,介绍了国内主要重金属污染场地修复技术,包括客土法、固化/稳定化技术、土壤淋洗法、解吸脱附技术、竖向隔离法和氧化还原技术,并进一步阐述了各个技术最新的科学研究进展和目前的国内工程应用情况,以期为重金属污染场地的修复工作提供借鉴和参考。     

化学钝化法修复重金属污染土壤研究进展

化学钝化修复是通过往土壤中加入钝化剂,以调节和改变重金属在土壤中的物理化学性质,使其发生氧化还原、沉淀、吸附、螯合、抑制或拮抗等一系列反应,降低其在土壤环境中的生物有效性和可迁移性,从而减少这些重金属元素对动植物的毒性.这种方法因投入低、效率高、修复快速、操作简单等优点,对大面积污染土壤的修复具有较好的应用前景.文中系统地综述了土壤重金属污染现状、危害、来源、特点及化学钝化修复技术的类型、作用机理、影响因素、修复实例,并分析了化学钝化技术的研究现状、存在的问题及未来的发展方向.     

吉林某弹药销毁场土壤炸药污染调查及其赋存状态研究

研究吉林某军事弹药销毁场土壤炸药污染程度以及炸药在土壤中的赋存状态,为炸药和重金属污染土壤修复提供针对性策略。采集了某弹药销毁厂焚烧销毁区表层土壤样品,分析了其理化性质和常见重金属元素含量,测试了土壤全样和不同颗粒度土壤样品中炸药污染物的含量,并结合热重-傅里叶变换红外光谱(TGA-FTIR) 对炸药污染土壤样品热力学行为的表征,探讨了炸药污染物的赋存状态,炸药和重金属组合污染特征等。土壤中含有高浓度的TNT、DNT、ADNT、RDX等炸药污染物及其降解产物,并表现出土壤细颗粒富集趋势,其中土壤全样中TNT总浓度达到了1.66×104 mg·kg-1,远远高于EPA推荐的土壤TNT指导限值,RDX超过了以土壤环境为目标的指导限值;销毁活动还造成了土壤中Pb、Cu、Zn重金属浓度的升高,分别为400 mg·kg-1,318 mg·kg-1,1030 mg·kg-1。土壤中受到重金属和有机质等因素的影响,土壤中经过长期老化的炸药污染物的热解行为明显不同于自由态的炸药分子,热解温度升高、过程延长。在销毁区炸药污染土壤的修复中,应加强炸药污染物与重金属相互作用的研究,并在修复治理实践中采取协同修复的策略。     

广州番禺试点重金属污染土壤修复

<正>土壤的重金属污染问题一直备受关注,2012年"垃圾肥"种菜事件也让番禺的土壤污染问题走进公众视线。记者不久前获悉,广东全省12个重金属重点防控区中,番禺占了3个,土壤修复任务很重。为此,番禺将开展重金属污染土壤修复试点工作,找到一套可推广、适合本地区的土壤污染     

冲积平原区土壤中重金属元素的存在形态分析

采用0.1mol／L氢氧化钠浸提腐殖酸的方法,将土壤中的腐殖酸及与腐殖酸结合的重金属元素分离出来;分别用分光光度法、原子荧光光谱法、等离子质谱法测定样品中腐殖酸及重金属元素的含量;初步测定结果显示：与腐殖酸结合的重金属元素是冲积平原区表层土壤中重金属元素的1种重要存在形态,而且可能是土壤中重金属污染元素主要的存在形式。     

铅污染土壤的修复技术

综述了铅对土壤的污染及其修复技术。目前应用于污染土壤的修复技术可分为物理化学修复技术和生物修复技术。物理化学修复技术又可分为隔离包埋技术,固化稳定技术,Pyrometalluryical separation,化学稳定技术,电动修复技术等;生物修复技术可分为微生物修复技术和植物修复技术等。以期进一步推动铅污染土壤的治理和修复工作。     

Ornamental Plant Efficiency for Heavy Metals Phytoextraction from Contaminated Soils Amended with Organic Materials

Accumulation of heavy metals (HMs) by ornamental plants (OPs) from contaminated agriculture soils is a unique technique that can efficiently reduce the metal load in the food chain. Amaranthus tricolor L. has attractive characteristics acquiring a higher growth rate and large biomass when grown at heavy metal contaminated soils. Site-specific detailed information is not available on the use of A. tricolor plant in metal phytoremediation from the polluted sites. The study aimed to enhance the uptake of HMs (Pb, Zn, and Cu) via amending poultry litter extract (PLE), vinasse sugarcane (VSC), and humic acid (HA) as natural mobilized organic materials compared to ethylene diamine tetraacetic acid (EDTA), as a common mobilized chemical agent by A. tricolor plant. The studied soils collected from Helwan, El-Gabal El-Asfar (Cairo Governorate), Arab El-Madabeg (Assiut Governorate), Egypt, and study have been conducted under pot condition. Our results revealed all organic materials in all studied soils, except EDTA in EL-Gabal El-Asfar soil, significantly increased the dry weight of the A. tricolor plant compared to the control treatment. The uptake of Pb and Zn significantly (p > 0.05) increased due to applying all organic materials to the studied soils. HA application caused the highest uptake as shown in Pb concentration by more than 5 times in Helwan soil and EDTA by 65% in El-Gabal El-Asfar soil while VSC increased it by 110% in El-Madabeg soil. Also, an increase in Zn concentration due to EDTA application was 58, 42, and 56% for Helwan, El-Gabal El-Asfar, and El-Madabeg soil, respectively. In all studied soils, the application of organic materials increased the remediation factor (RF) than the control. El-Madabeg soil treated with vinasse sugarcane gave the highest RF values; 6.40, 3.26, and 4.02% for Pb, Zn, and Cu, respectively, than the control. Thus, we identified A. tricolor as a successful ornamental candidate that, along with organic mobilization amendments, most efficiently develop soil health, reduce metal toxicity, and recommend remediation of heavy metal-contaminated soils. Additionally, long-term application of organic mobilization amendments and continued growth of A. tricolor under field conditions could be recommended for future directions to confirm the results.     

Assessment of heavy metal background values in the soils of inland coastal areas of Venice,Italy

The main aim of this project was to assess background levels of heavy metals in soil in the inland coastal area of Venice, Italy. The pilot study area is located near the industrial area of Porto Marghera, considered of national interest in terms of contaminated soil remediation (Environmental Ministerial Decree n. 471/1999). The Decree under consideration emphasises the importance of the assessment of background values in soil remediation. Results will show cases (As and Sn) in which background values are greater than concentration limit standards given by legislation.     

生物材料对重金属离子的吸附富集作用

介绍了重金属离子的生物吸附富集作用,从生物材料的类型、生物吸附的选择性、化学修饰与生物吸附、生物对重金属离子的浓缩富集作用和生物吸附的机理及模型等方面作了说明。利用生物材料可去除水体中的重金属离子。     

Treatment of the solution extracted from metal contaminated soils by reverse osmosis and chemical precipitation

In this study a process for the remediation of soils contaminated by lead or copper is proposed, consisting of the operations in sequence: soil flushing, membrane treatment, acidification, and metal precipitation. Pb(II) and Cu(II) extraction from a synthetically contaminated soil using a 0.05 M EDTA aqueous solution were investigated in column. The metal removal efficiencies and the final soil metal concentration were 98.2% and 37.96 mg/g respectively for lead and 95.4% and 59.20 mg/kg for copper. The extracted solutions were concentrated through a membrane treatment to reduce the water content up to the 75% and to obtain a permeate metal concentration in compliance with the Italian Environmental Regulation. The recovery of the used EDTA from the retentate solution, with recovery yield of at least 85.4%, was also obtained through acidification. Metal precipitation from the filtered solution was then performed according two different methods, achieving metal removal yield of more than 99.4%.     

Biochemical Basis of Mercury Remediation and Bioaccumulation by Enterobacter sp. EMB21

The aims of this study were to isolate metal bioaccumulating bacterial strains and to study their applications in removal of environmental problematic heavy metals like mercury. Five bacterial strains belonging to genera Enterobacter, Bacillus, and Pseudomonas were isolated from oil-spilled soil. Among these, one of the strains Enterobacter sp. EMB21 showed mercury bioaccumulation inside the cells simultaneous to its bioremediation. The bioaccumulation of remediated mercury was confirmed by transmission electron microscopy and energy dispersive X-ray. The mercury-resistant loci in the Enterobacter sp. EMB21 cells were plasmid-mediated as confirmed by transformation of mercury-sensitive Escherichia coli DH5α by Enterobacter sp. EMB21 plasmid. Effect of different culture parameters viz-a-viz inoculum size, pH, carbon, and nitrogen source revealed that alkaline pH and presence of dextrose and yeast extract favored better remediation. The results indicated the usefulness of Enterobacter sp. EMB21 for the effective remediation of mercury in bioaccumulated form. The Enterobacter sp. EMB21 seems promising for heavy metal remediation wherein the remediated metal can be trapped inside the cells. The process can further be developed for the synthesis of valuable high-end functional alloy, nanoparticles, or metal conjugates from the metal being remediated.     

Electron Microscopy of Rhamnolipid (Biosurfactant) Morphology: Effects of pH, Cadmium, and Octadecane

A rhamnolipid biosurfactant produced by Pseudomonas aeruginosa ATCC 9027 is reported to increase the aqueous dispersion and biodegradation of petroleum hydrocarbons and to complex heavy metals. These reports indicate the potential for application of rhamnolipids in remediation of contaminated sites. Effective use of rhamnolipids will require understanding of rhamnolipid morphology and the effects of pH and organic and inorganic contaminants on that morphology. We used cryo-transmission electron microscopy to investigate the morphology of vitrified, frozen hydrated suspensions of rhamnolipid over a pH range of 5.5 to 8.0, and to determine the effect of a model alkane, octadecane, and a model heavy metal, cadmium, on rhamnolipid morphology. Micrographs clearly showed that rhamnolipid morphology was a function of pH, changing from lamellar, to vesicular, to micellar as pH increased. The effect of cadmium and octadecane on rhamnolipid morphology was determined at pH 6.8 and 7.0, where maximum cadmium complexation and maximum octadecane dispersion occurs. Cadmium seemed to stabilize rhamnolipid vesicle structures as shown by an increase in vesicle number and a decrease in vesicle diameter. In contrast, octadecane favored the micellar structure as shown by the complete absence of vesicles.     

Prospective of Microbial Exopolysaccharide for Heavy Metal Exclusion

Metals as a resource are depleting, and on another side, it fetches serious environmental pollution causing a threat to human health and ecosystem. The heavy metal accumulation due to anthropogenic activities results in toxicological manifestation. The traditional methods of remediation are not cost effective, efficient, and ecofriendly which necessitate and motivate towards the safe, effective, and ecofriendly biological methods. The increasing presence of heavy metals in the microbial habitat compels the microbes to develop the ability to tolerate or resist the presence of heavy metals. Exopolysaccharide (EPS) production is one of the strategies of microbes to fight against metal stress. EPS is a microbial biopolymer which is generally produced under stress from harsh environment and nutrition conditions. EPSs are cell-associated or secreted outside the cell and comprised organic macromolecules such as polysaccharides, proteins, and phospholipids in addition to some non-polymeric molecules. EPSs work as competent biosorbents with an anionic reactant group that effectively sequesters cationic heavy metals by electrostatic interactions. The present paper summarizes the EPSs with its types, role, and biosynthesis and an endeavor to elucidate the interaction mechanism of EPSs with heavy metal with supportive and distinctive applications for heavy metal exclusion. The review concluded with the current challenges and future prospects to make the EPS an efficient biosorbent.     

Extraction procedures for the determination of heavy metals in contaminated soil and sediment

Extraction tests are commonly used to study the mobility of metals in soils and sediments by mimicking different environmental conditions or dramatic changes on them. The results obtained by determining the extractable elements are dependent on the extraction procedure applied. The paper summarises state of the art extraction procedures used for heavy metal determination in contaminated soil and sediments. Two types of extraction are considered: single and sequential. Special attention is paid to the Standard, Measurement and Testing projects from the European Commission which focused on the harmonisation of the extraction procedures and on preparing soil and sediment certified reference materials for extractable heavy metal contents.