重金属与土壤微生物的相互作用及污染土壤修复

阐述了微生物与重金属间的相互作用，指出土壤重金属污染影响微生物活性、生物量，且重金属对微生物具有一定的生态毒性。可通过微生物的氧化-还原作用、生物吸附富集和溶解作用，达到修复重金属污染土壤的目的。     

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.     

农药污染与土壤微生物

随着工业的发展,“三废”、农药、化肥、塑料制品对农田的污染越来越严重了。污染物进入土壤后既污染了环境,又使土壤生态系统结构发生变化。土壤微生物是土壤生态系统中的主要分解者,其活动是衡量生态系统中各种功能是否正常的一个重要方面。因为微生物在转化有机质的过程中对重金属的迁移转化、有机毒物的分解能起到积极的作用,因而能减少污染物的毒性。但是,高浓度的环境污染物却能使微生物的生长发育受到抑制。本文仅就有机污染物对土壤微生物的影响和微生物对污染物的转化或解毒作用作一简要综述。     

黑麦草修复重金属污染土壤与废水及富集植物的微生物降解

为了研究黑麦草(Lolium perenne)修复复合重金属污染土壤与废水的综合利用效应,探索微生物对富集重金属黑麦草的降解效果,以复合重金属污染的土壤与废水为修复对象,利用黑麦草对土壤和废水进行修复,并考察了黑麦草的重金属含量、富集量、富集系数和转移系数。采用8种微生物对富集重金属黑麦草进行降解,考察黑麦草的失重率,黑麦草纤维素、半纤维素和木质素的变化情况以及重金属的浸出效果。结果表明:黑麦草对重金属污染的土壤与水体均具有较好的修复效果;在土壤修复阶段,黑麦草对U的富集系数最大,达到7.43;而对Cd的富集系数为2.61,对Pb和Sr的修复效果不明显;在废水修复阶段,黑麦草对U的富集量达到1 213.70 mg·kg-1DW,U、Cr、Sr、Co的富集系数和转移系数均大于1,其中U的富集系数达到11.24。另外,里氏木霉(Trichoderma ressei)和黄孢原毛平革菌(Phanerochaete chrysosporium)对富集黑麦草的总降解率达到60%以上;里氏木霉(Trichoderma ressei)、枯草芽孢杆菌(Bacillus subtilis)和地衣芽孢杆菌(Bacillus lincheniformis)对重金属的平均浸出率分别达到87.19%、90.58%和90.33%。在重金属污染的土壤和水体中,通过对黑麦草的循环使用,可以提高黑麦草的综合利用效率,有效减少富集生物质的产生;同时微生物对富集生物质有较好的降解能力。研究为重金属富集生物质微生物处置以及重金属回收技术奠定基础。     

训练场土壤重金属污染治理的对策探讨

土壤重金属的污染防治,是环保领域面临的一个重大课题。土壤重金属的污染在军事区域同样存在,污染场所主要包括子弹打靶场、坦克射击场以及炮弹落弹区等。重金属污染的元素包括Pb、Cu、Zn、Co等。训练场土壤重金属污染的治理,既要对已经污染的土壤根据其污染特征,采取相应的物理化学或者植物修复措施,又要从污染源头上下手,降低或者彻底杜绝训练场土壤的重金属污染。     

磷矿粉修复重金属污染土壤的研究进展

重金属污染土壤的化学钝化修复技术可以有效控制重金属对植物及环境的危害。不同的改良剂对重金属污染土壤的改良效果不同,已有的研究表明难溶性磷矿粉是较好的选择。磷矿粉是一种性价比很高的改良剂,而且不会对环境造成破坏。总结了磷矿粉修复重金属污染土壤的化学机制和影响因素,重点综述了近年来不同粒径磷矿粉、改性磷矿粉修复重金属污染土壤的研究进展,旨在为重金属污染土壤的修复研究提供参考。     

粘土矿物修复重金属污染土壤

简要介绍了我国土壤重金属污染的现状与危害.通过粘土矿物在重金属污染土壤中净化功能的阐述,提出利用粘土矿物修复土壤重金属污染的观点.继而从天然和改性粘土矿物特性,叙述了粘土矿物修复土壤重金属污染的机制与应用进展及其影响因素.最后讨论了粘土矿物在修复土壤重金属污染过程中值得注意的几个问题,并展望了粘土矿物在该领域应用中的发展方向.     

功能微生物对污染农田土壤中铅锌的溶出实验

用微生物修复重金属污染的土壤是当今的研究热点之一。试图寻找一类可以增加土壤中重金属铅、锌的可溶态的功能微生物,并研究该微生物在不同土壤含水率和不同投菌比条件下对铅、锌溶出作用的影响。最终筛选出符合条件的菌JK3,并发现当土壤含水率为35%,投菌比为0.15 mL/g土(菌液OD=1)时,土壤中铅和锌的可溶态增加量最多。其中,可溶态铅的含量由原来的0.49 mg/kg增加到了5.04 mg/kg,可溶态锌的含量由原来的2.23 mg/kg增加到了22.44mg/kg。该方法为后续用植物提取或化学淋洗等方法将土壤中的重金属彻底去除提供了可能。     

土壤及土壤-植物系统中复合污染的研究进展

土壤复合污染是土壤污染的主要存在形式 ,在分析中 ,主要从土壤重金属复合污染和土壤重金属 有机污染物复合污染方面进行了较为全面的综述 ,评价了土壤复合污染的多种表征方法 ,并且讨论了该研究当前仍存在的一些问题     

土壤重金属污染损害赔偿实现路径研究

土壤是动植物赖以生存的载体,重金属污染不仅严重侵害人体健康,而且破坏土壤耕作功能。土壤重金属污染具有涉及面广、受害人多、技术性强等特点,加之因果关系认定与证据收集难度大,促使受害人的权利救济遭遇现实困境。建议在严格责任、修复费用次优受偿、惩罚性赔偿等原则指引下,完善能实现受害者联合、节约司法资源、促进企业产业升级的集团诉讼制度;建构以"重金属污染基金制度"与"重金属污染责任保险制度"为主要路径的中国土壤重金属污染损害的社会化救济机制。     

Influence of Phenanthrene on Cadmium Toxicity to Soil Enzymes and Microbial Growth (5 pp)

Background Many contaminated sites contain a variety of toxicants. Risk assessment and the development of soil quality criteria therefore require information on the interaction among toxicants. Interactions between heavy metals are relatively well studied, but little is known about those between heavy metals and polycyclic aromatic hydrocarbons (PAHs). Methods 0.1 mg/kg dry soil phenanthrene alone or phenanthrene plus 10 mg/kg cadmium (Cd) were added to soil to determine the influence of phenanthrene on Cd toxicity to soil enzymes (invertase, urease, dehydrogenase and phosphatase) and microorganisms (fungi, bacteria and actinomycete) in paddy soil. Results and Discussion 0.1 mg/kg phenanthrene did not reduce the number of microorganisms. However, the addition of phenanthrene to soil with Cd enhanced the Cd toxicity to soil enzymes and microorganisms. This deleterious effect was seen to mainly affect the growth of fungi and the activity of invertase, urease and dehydrogenase. The order of combined inhibition of Cd and phenanthrene was fungi>bacteria>actinomycete. Conclusion The presence of phenanthrene might enhance the toxicity of Cd to soil microorganisms. Phenanthrene can easily be used by the soil actinomycetes as a source of carbon and energy and the finding may be supportive to the development of bioremediation techniques.     

Progress in decontamination by halophilic microorganisms in saline wastewater and soil

Environments with high-salt concentrations are often populated by dense microbial communities. Halophilic microorganisms can be isolated from different saline environments and different strains even belonging to the same genus have various applications. Wastewater and soil rich in both organic matter and salt are difficult to treat using conventional microorganisms typically found in wastewater treatment and soil bioremediation facilities. Studies on decontaminative capabilities and decontamination pathways of organic contaminants (i.e., aromatic compounds benzoate, cinnamate, 3-phenylpropionate, 4-hydroxybenzoic acid), heavy metals (i.e., tellurium, vanadium), and nutrients in the biological treatment of saline wastewater and soil by halophilic microorganisms are discussed in this review.     

Indigenous soil bacteria with the combined potential for hydrocarbon consumption and heavy metal resistance

Introduction  

Transconjugant bacteria with combined potential for hydrocarbon utilization and heavy metal resistance were suggested by earlier investigators for bioremediation of soils co-contaminated with hydrocarbons and heavy metals. The purpose of this study was to offer evidence that such microorganisms are already part of the indigenous soil microflora.     

微生物抗重金属毒性研究进展

不少重金属是微生物正常生长的必需元素 ,但是当重金属在菌体内浓度过高时 ,会对菌体产生毒性。微生物可通过细胞的表面富集与细胞膜成分的改变减小毒性的破坏 ,在重金属进一步的诱导下 ,菌体会产生由结构基因与调节基因组成的抗性基因 ,通过多途径的联合作用对重金属的毒性进行解毒     

Response of microbial activities to heavy metals in a neutral loamy soil treated with biosolid

Application of biosolid on land has been widespread in numerous countries for last several decades. This study performed incubation experiments by mixing a neutral loamy soil and biosolid enriched in Cu, Pb and Zn to explore how heavy metal affects soil mineralization and microbial biomass. The experimental results indicated that large nutrient, microorganism and C sources from biosolid were beneficial to microbial respiration. However, compared to the biosolid alone treatment, the supplemented Cu, Pb and Zn in biosolid reduced the mineralized C by roughly 36%. This phenomenon was probably caused by a portion of the Cu, Pb and Zn being complexed with organic matter to prevent decomposition of organic carbon by microorganisms. Equally, soil treated with biosolid increased the quantity of mineralized N by approximately five-fold and accelerated the rate of N mineralization by about one-fold compared to untreated soil. Notably, addition of heavy metals impaired the mineralization process, particularly when Pb reached about 64%. The reduced N mineralization occurred for similar reasons to the microbial respiration. The addition of biosolid in soil considerably increased the amount of mineralizable N; however, the increase was lower in biosolid-treated soil spiked by heavy metals. The addition of heavy metals in the soil-biosolid mixture clearly reduced the microbial biomasses C (MBC) and N (MBN), indicating that the microbial activities had been disrupted by the heavy metals. The microbial biomass C/N ratio had changed initially from 8 to 13 at the end of incubation period, owing to various groups of microbes expressing different mechanisms of metabolism, indicating that the microbial population had changed from bacteria to fungi, which had higher metal tolerance.     

Microbial cellulose decomposition in soils from a rifle range contaminated with heavy metals

The objective of this study was to assess the effects of heavy metals on microbial decomposition of cellulose in heavy metal-contaminated soils using a cotton strip assay. The assay is a measure of the potential of soil microorganisms to decompose the plant polymer, cellulose. Cellulolytic activity in soil was assessed by determining the reduction in tensile strength of the buried cotton strips over a 25- and 45-day period. Soils were obtained from a rifle range that contain high levels of lead, copper and zinc. The site has been used for approximately 50 years, resulting in metal levels of up to 30,000 mg/kg of lead, 4000 mg/kg of copper and 600 mg/kg of zinc in the most contaminated soils. All the metal-contaminated soils had lower degradation rates than the uncontaminated soils tested. Among the contaminated soils, however, the heavy metal concentration was not the major factor in determining the loss in tensile strength of the cotton strips, where cellulose decomposition was governed by other soil physicochemical properties. Soil with a higher cation exchange capacity, readily oxidisable material and volatile solids content had the greatest loss in tensile strength of cotton strips. Microbial adaptation to the presence of high concentrations of soil heavy metals and reduced bioavailability of metals is the likely explanation for this phenomenon.     

Reduction of bioavailability and leachability of heavy metals during vermicomposting of water hyacinth

Vermicomposting of water hyacinth is a good alternative for the treatment of water hyacinth (Eichhornia crassipes) and subsequentially, beneficial for agriculture purposes. The bioavailability and leachability of heavy metals (Zn, Cu, Mn, Fe, Ni, Pb, Cd, and Cr) were evaluated during vermicomposting of E. crassipes employing Eisenia fetida earthworm. Five different proportions (trials 1, 2, 3, 4, and 5) of cattle manure, water hyacinth, and sawdust were prepared for the vermicomposting process. Results show that very poor biomass growth of earthworms was observed in the highest proportion of water hyacinth (trial 1). The water soluble, diethylenetriaminepentaacetic acid (DTPA) extractable, and leachable heavy metals concentration (percentage of total heavy metals) were reduced significantly in all trials except trial 1. The total concentration of some metals was low but its water soluble and DTPA extractable fractions were similar or more than other metals which were present in higher concentration. This study revealed that the toxicity of metals depends on bioavailable fraction rather than total metal concentration. Bioavailable fraction of metals may be toxic for plants and soil microorganisms. The vermicomposting of water hyacinth by E. fetida was very effective for reduction of bioavailability and leachability of selected heavy metals. Leachability test confirmed that prepared vermicompost is not hazardous for soil, plants, and human health. The feasibility of earthworms to mitigate the metal toxicity and to enhance the nutrient profile in water hyacinth vermicompost might be useful in sustainable land renovation practices at low-input basis.     

Effects of mycorrhizae and other soil microbes on revegetation of heavy metal contaminated mine spoil

The effects of mycorrhizal fungi and other soil microorganisms on growth of two grasses, Andropogon gerardii Vitm. and Festuca arundinacea Schreb., in heavy metal-contaminated soil and mine tailings were investigated. A. gerardii is highly dependent on mycorrhizal fungi in native prairie, while F. arundinacea is a facultative mycotroph and relies on mycorrhizal symbiosis only in extremely infertile soils. Regardless of microbial amendments, neither plant species was able to establish and grow in the mine tailings. Both plant species grew in the moderately contaminated or non-contaminated soils, although A. gerardii grew in these soils only when mycorrhizal. Other soil microbes significantly improved growth of A. gerardii only in uncontaminated soil, but to a lesser extent than mycorrhizae. Although F. arundinacea was more highly colonized by mycorrhizal fungi than A. gerardii, neither microbial amendment affected growth of fescue in any soil. In several treatments mycorrhizal fungi adapted to uncontaminated soil stimulated plant growth more than mycorrhizae adapted to the moderately contaminated soil. However, mycorrhizal fungi adapted to contaminated soil did not increase the productivity of plant growth in contaminated soil more than fungi adapted to uncontaminated soil. A. gerardii plants inoculated with mycorrhizal fungi retained more Zn in roots than in shoots, confirming earlier reports that mycorrhizal fungi alter the translocation pattern of heavy metals in host plants. In contrast, mycorrhizae did not affect translocation patterns in F. arundinaceae, suggesting that the mycorrhizal dependence of a plant species is correlated with the retention of metals in roots. The correlation between mycorrhizal dependence of a plant species and mycorrhizal alteration of translocation pattern may also explain the inconsistent reports of mycorrhizal effects on translocation of heavy metals in plants. Plant response to mycorrhizal symbiosis may therefore provide a useful criterion for the selection of the plant species to be used in revegetation of contaminated sites.     

层次分析法与地理信息系统在农田土壤重金属污染评价中的应用

以《土壤环境质量标准》(GB 15618—1995)二级标准作为评价标准,采用以改进层次分析法确定权重的加权平均法对南京市郊典型蔬菜地的土壤重金属污染状况进行了评价。结果表明,研究区土壤中Cu、Pb、Cr的单因子污染指数平均值均小于1,含量超标率均不超过10.32%,而Cd的单因子污染指数平均值达2.15,含量超标率为84.13%,急需对该区土壤和受体做进一步的Cd污染深入调查或风险评估;研究区土壤重金属综合污染指数平均值为1.28,属玷污水平;利用ArcGIS 8.3软件进行土壤重金属污染的空间分布特征分析结果表明,研究区各元素的污染程度为Cd>Pb>Cu>Cr,各元素的污染格局较为相似,城市化活动对土壤污染贡献较大;研究区有81.16%的土壤重金属污染级别为玷污,3.78%处于本底级,15.06%处于安全级。