生物在重金属污染土壤修复中的应用研究

土壤是人类赖以生存的自然资源之一。随着工农业生产的发展,土壤重金属污染现象越来越严重。目前生物修复技术已开始成为土壤重金属污染修复的主要处理技术,该文系统介绍了主要生物修复方法的研究进展,并在此基础上提出了其中存在的问题及研究展望。     

环境友好型土壤重金属修复技术及其应用

针对全球土壤重金属污染不容忽视的现状,国内外学者在土壤修复方面进行了大量研究。当前的土壤修复政策和评价标准主要指向土壤中重金属总量的减少,忽略了重金属的形态变化。然而重金属形态才是影响其生物有效性和毒性的关键因素。2019年我国农业农村部规定在土壤污染的治理中,在达成基本目标的同时应优先考虑修复方法对土壤性质的损伤风险以及环境污染风险,防止二次污染,保证耕地可持续利用。因此,如何在对土壤环境产生最低甚至无损害的前提下减少重金属总量或改变重金属形态从而降低其风险是土壤污染修复的热点。虽然土壤重金属污染修复技术众多,但目前对土壤无损伤且有效的土壤修复技术有固定/稳定化、植物和微生物修复这三种。固定/稳定化技术可以短期内降低土壤重金属有效性,但易失去钝化效果,导致被固定重金属的重新活化;植物、微生物修复可稳定改变重金属有效性和总量,但其修复周期长,环境限制大。本文主要就上述三种环境友好型修复技术进行了总结分析,阐述了各修复技术的作用机制、优缺点、环境风险和应用前景,并从提高重金属生物有效性、调节生物代谢活动、吸附钝化重金属、改善土壤修复环境四个方面阐述了不同强化方式的原理、修复效果、优势以及...     

污染土壤修复技术研究现状与趋势分析

污染土壤中存在农药残留与重金属等有害物质,会对周边的农业、养殖业发展造成影响,出现食品安全问题,阻碍当地的经济发展。基于此,污染土壤修复技术成为学术界研究的热点,该文从生物、化学与物理3个角度入手,分析污染土壤修复技术的研究现状,明确污染土壤修复中各项技术的应用效果、适用范围与优缺点等,并阐述了污染土壤修复技术的研究趋势,为专家学者研发新型污染土壤修复技术提供参考,切实解决土壤污染问题,保护生态环境。     

微生物治理土壤重金属污染的研究进展

近年来,土壤重金属污染问题日益严重,对其的治理已成为当今的热点话题。本文根据国内外的研究成果对微生物用于土壤重金属污染治理进行了综述,介绍了微生物修复技术、微生物展示技术、微生物和植物联合修复,以及它们的概念、基本原理和研究进展等,并展望了其发展前景。     

土壤重金属污染用微生物修复的研究

土壤重金属污染物在土壤中的存在用微生物修复方法。重金属土壤污染问题迫切需要解决,治理重金属污染,从生物修复方面阐述了重金属的治理方法、手段,微生物修复的可行性和环保等优点。     

浅议土壤重金属污染修复技术

随着全球工业的逐渐发展,土壤重金属污染逐渐成为了一种全球性的问题,对土壤重金属污染的治理也成为了广大环境工作者亟待解决的热点问题。本文通过对土壤重金属污染危害的分析,结合笔者实际研究经验,就现阶段土壤重金属污染修复问题提出了几点技术性的建议。     

胡敏素在土壤重金属污染修复中的研究进展

研发功能性明显、安全和经济实用的环境材料是修复土壤重金属污染研究领域的一个重要方向.胡敏素是土壤有机质的重要组分,具有分子量大和不溶于酸碱溶液等特征,对土壤重金属的转化、迁移等方面起到关键性作用.对胡敏素来源、性质和修复土壤重金属污染的机制进行总结分析.提出胡敏素对土壤重金属污染的修复机理主要包括离子交换、静电吸附、物...     

土壤重金属固化稳定化的环境材料研究进展

固化稳定化是土壤重金属污染治理的主要技术之一,固化材料的环境材料理念加强尤为重要。环境材料是具有最低环境负荷和最大使用功能的人类所需材料,具有功能性、环境友好性和经济性三大特征。我国农田土壤重金属点位污染达到19.1%;治理途径有物理技术、化学技术、生物技术;化学技术有淋洗和固化稳定化(S/S)技术,实际应用中70%以上土壤重金属污染治理技术选择后者。固化稳定化的环境材料的类别可分为无机材料、有机材料和氧化还原材料;环境材料的应用应结合重金属类别及其污染程度、修复目标和当地的土壤、气候和社会经济条件等因素,并与生物技术和工程技术等集成。结合国内外土壤重金属固化稳定化的研究进展,总结了土壤重金属污染治理的环境材料作用机理,主要包括沉淀作用、吸附作用、配位作用、有机络合和氧化还原作用等,核心是改变重金属在土壤中的赋存形态和化学形态,降低其迁移性和生物有效性;围绕土壤重金属固化稳定化研究的系统化,提出土壤重金属污染治理的应用基础研究框架,包括材料与重金属、材料-土壤-重金属、材料-土壤-植物-重金属、材料-田间-作物-重金属以及重金属治理的综合评价等5个层次,这是促进环境材料基础与应用研究结合的基础。     

纳米TiO2光催化材料在环境土壤修复中的应用研究进展

近年来对土壤污染的综合治理和修复已经成为环保领域的一个研究热点,光催化技术修复污染土壤是一种操作简便、费用低廉、无二次污染和具有广阔发展前景的新兴技术。分析了光催化技术修复污染土壤的原理,并综述了近年来纳米 TiO2光催化材料在土壤有机物污染物(农药、芳香族类和石油类等)的降解以及重金属离子(Ag+、Cr6+等)的光催化还原研究进展,并提出了未来的发展方向和建议。     

治理食品污染需用重典

前不久，国家工商总局公布的2004年第四季度在全国范围内对10类重点食品质量监测报告表明，水产品重金属严重超标。由于近年来海水污染日益严重，出现了海产品重金属镉超标现象。中国科学院地理科学与资源研究所环境修复中心主任、国家高技术发展研究计划“重金属污染土壤的植物修复技术与示范”课题首席科学家陈同斌研究员在接受记者采访时指出，随废水排出的重金属一旦进入河流、湖泊和海洋，就会被藻类、鱼类、     

Removal of Cu, Pb and Zn in an applied electric field in calcareous and non-calcareous soils

The pH dependency of the removal of Cu, Zn and Pb by electrodialytic soil remediation from different industrially polluted soils was examined. From 18 experiments performed with five different soils, it was found that the order of mobilization due to a pH decrease was Zn>Cu>Pb. It was found, too, that each of the elements was removed at higher soil pH in calcareous soils (about 12% carbonates) than in soils with a carbonate content of less than 3.7%. In soils rich in carbonates, precipitation of heavy metal carbonates is an important retention mechanism and the heavy metal carbonates are dissolved at higher pH values than the pH at which heavy metals are desorbed in non-calcareous soils. Thus, the relation between the soil pH and the mobility of the heavy metal in the electric field is not only dependent on the heavy metal in focus, but also on the fraction of the heavy metal precipitated as carbonates.     

Enhanced electrokinetic extraction of heavy metals from soils assisted by ion exchange membranes

The potential of electrokinetic remediation technology has been successfully demonstrated for the remediation of heavy metal contaminated fine-grained soils through laboratory scale and field application studies. Various enhancement techniques have been proposed and used in order to further improve the remediation process. However, it has been reported that such enhancement schemes can create other obstacles, such as the introduction of non-target ions into the system and thereby decrease the efficiency of the remediation process. Electrokinetic soil remediation technology enhanced by an ion exchange membrane (IEM), IEM-enhanced EK processing, was experimentally evaluated for the purpose of overcoming these obstacles. In particular, this study focused on observations of a fouling problem and its settlement using an auxiliary solution cell (ASC). In addition, the efficacies of two different types of electrode configurations, rectangular and cylindrical, were investigated. The experimental results indicate that the effectiveness of the technology was increased by an enhancement scheme using an IEM. This may be explained by the prevention of metal precipitation in the region near the cathode originating from hydroxide ions generated by the electrolysis of water in the cathode. The experimental results also imply that placement of the ASC can nullify the fouling problem within the cation exchange membranes used in IEM-enhanced EK processing, and thus improve the overall effectiveness of the process. The experimental results indicate that the cylindrical electrode configuration can be implemented in practical situations to improve the treatability of cathode effluent containing a high level of contaminants after processing.     

Soil washing for metal removal: a review of physical/chemical technologies and field applications

Soil washing is one of the few permanent treatment alternatives to remove metal contaminants from soils. This paper reviews the various technology types and pilot/full-scale field applications of soil washing applicable to soils highly contaminated with heavy metals. The physical separation technologies, the chemical extraction processes and the integrated processes that combine both physical and chemical methods are discussed separately. This paper reviews basic principles, applicability, advantages and limitations, methods of predicting and improving performance of each physical/chemical technology. The discussion is based on a review of 30 recent laboratory investigations and 37 field applications of soil washing systems which have been undertaken, mostly in the US, for the period 1990-2007. This paper also examines and compares the status of soil washing technology for remediation of soils contaminated with metals in the US, in Canada and in Europe.     

Growth response of Zea mays L. in pyrene-copper co-contaminated soil and the fate of pollutants

Phytoremediation, use of plants for remediation, is an emerging technology for treating heavy metals or a final polishing step for the high-level organic contamination, and may be suitable for remediation of heavy metal and organic co-contaminated soil. The aim of this study was to investigate the influence of co-contamination on the growth of Zea mays L. and the fate of both heavy metal and organic pollutants, using Cu and pyrene as the model pollutants. Results showed that shoot and root biomass were affected by the copper–pyrene co-contamination, although maize grown in spiked soils showed no outward signs of phytotoxicity. With the initial concentration of 50,100 and 500 mg/kg, pyrene tended to alleviate the inhibition of Cu to Z. mays L. Pyrene in both planted and non-planted soil was greatly decreased at the end of the 4-week culture, accounting for 16–18% of initial extractable concentrations in non-planted soil and 9–14% in planted soil, which indicated that the dissipation of soil pyrene was enhanced in the presence of vegetation probably due to the biodegradation and association with the soil matrix. With the increment of Cu level, residual pyrene in the planted soil tended to increase. The pyrene residual in the presence of high concentration of Cu was even higher in the planted soil than that in the non-planted soil, which suggested that the change of the microbial composition and microbial activity or the modified root physiology under Cu stress was probably unbeneficial to the dissipation of pyrene. A more thorough understanding of the mechanisms by which metals affect the dissipation of organic pollutants in the rhizosphere could provide a much better framework on which to base manipulation. Unlike pyrene, heavy metal copper cannot be degraded. Decontamination of Cu from contaminated soils in this system required the removal of Cu by plants. It was observed that the ability of Cu phytoextraction would be inhibited under co-contamination of high level of pyrene in highly Cu-polluted soil. In the treatment of 400 mg Cu/kg and 500 mg pyrene/kg, the accumulation of Cu was less than half of that in 400 mg Cu/kg treatment.     

燃煤电厂脱硫废水及污泥中重金属污染物控制研究进展

燃煤发电中常采用湿法烟气脱硫技术,该工艺会产生含有重金属污染物的脱硫废水和污泥,潜在环境危害性强,需谨慎处理。介绍了燃煤电厂脱硫废水和脱硫污泥的产生来源、成分组成、重金属污染物含量水平和排放处置标准,对沉淀法等脱硫废水重金属处理技术和脱硫污泥重金属去除及固化技术的原理、优点、适用性和局限性进行总结对比分析。脱硫废水重金属控制方法中,目前普遍使用的三联箱工艺难以满足日益严格的排放标准,需进行改进;吸附法、微生物法等新型方法也因成本和技术等问题而难以普及;零排放技术因其无污染的特性将逐渐成为研究和推广的主流。脱硫污泥重金属控制方法大多仍处于研究中,化学修复和药剂固化方法因效果好、适用性强将逐渐在电厂生产实践中推广。     

Progress in the remediation of hazardous heavy metal-polluted soils by natural zeolite

Hazardous heavy metal pollution of soils is an increasingly urgent problem all over the world. The zeolite as a natural amendment has been studied extensively for the remediation of hazardous heavy metal-polluted soils with recycling. But its theory and application dose are not fully clear. This paper reviews the related aspects of theory and application progress for the remediation of hazardous heavy metal-polluted soils by natural zeolite, with special emphasis on single/co-remediation. Based on the comments on hazardous heavy metal behavior characteristics in leaching and rhizosphere and remediation with zeolite for heavy metal-polluted soils, it indicated that the research of rhizosphere should be strengthened. Theory of remediation with natural zeolite could make breakthroughs due to the investigation on synthetic zeolite. Co-remediation with natural zeolite may be applied and studied with more prospect and sustainable recycling.     

Kinetics as a tool to assess the immobilization of soil trace metals by binding phase amendments for in situ remediation purposes

Many soil remediation techniques consist in decreasing the mobility of trace metals by means of adding trace metal binding phases. For this study, whose aim is to assess the efficiency of soil remediation method by binding phase amendment, a kinetic fractionation method that provides the labile and slowly labile trace metal amounts in soil has been introduced. Manganese oxides (vernadite) and insolubilized humic acids (IHA) have been used as binding phases for the remediation of four heavily polluted soils. Vernadite amendments are effective for lead and cadmium remediation, whereas IHA amendments are only effective for copper remediation. In most cases, the labile metal fractions decrease dramatically in amended soils (up to 50%); on the other hand, the amounts of total extracted metal near the point of thermodynamic equilibrium often show no significant difference between the amended soil and the control soil. These results highlight the utility of kinetic fractionation in assessing the efficiency of soil remediation techniques and, more generally, in evaluating trace metal mobility in soils and its potential advantages compared to extraction schemes performed under equilibrium conditions. In the future, this kinetic method could be considerably simplified so as to consume much less time allowing its routine use.     

The remediation of heavy metals contaminated sediment

Heavy metal contamination has become a worldwide problem through disturbing the normal functions of rivers and lakes. Sediment, as the largest storage and resources of heavy metal, plays a rather important role in metal transformations. This paper provides a review on the geochemical forms, affecting factors and remediation technologies of heavy metal in sediment. The in situ remediation of sediment aims at increasing the stabilization of some metals such as the mobile and the exchangeable fractions; whereas, the ex situ remediation mainly aims at removing those potentially mobile metals, such as the Mn-oxides and the organic matter (OM) fraction. The pH and OM can directly change metals distribution in sediment; however oxidation-reduction potential (ORP), mainly through changing the pH values, indirectly alters metals distribution. Mainly ascribed to their simple operation mode, low costs and fast remediation effects, in situ remediation technologies, especially being fit for slight pollution sediment, are applied widely. However, for avoiding metal secondary pollution from sediment release, ex situ remediation should be the hot point in future research.