低放核素污染土-水介质的植物修复研究进展

植物修复技术是利用植物根系吸收水分和养分的过程来吸收和转化土壤和水体中的污染物,以期达到清除,修复和治理的目的,是用于对土壤-水体中重金属和放射性核素污染清除的生态技术.本文就放射性核素的来源、污染现状、植物对放射性核素的积累筛选以及对污染土壤的修复研究进行综述,以明确植物修复技术在改善环境中的作用,为进一步筛选超积累植物并探讨植物对放射性核素污染的修复机理提供参考.     

有机物及重金属植物修复研究进展

植物修复技术是近年来发展起来的一种非常有前途的生物治理技术 ,也是当前学术界研究的热点领域 .本文对植物修复的类型 ,植物修复土壤、水体有机污染物、重金属和某些放射性核素的过程、机理及可能影响因子作了概括和详尽讨论 ,并就国内外近年来植物修复技术在污染环境中的应用和研究成果进行了综述     

有机污染环境的植物修复研究进展

分析了近年来国内外的文献资料,对有机污染物污染环境的植物修复研究进展作了综述。植物能通过根系从环境中吸收和积累PCBs、PAHs等有机污染物,并将吸收的TNT、TCE及有机农药降解为高极性产物、水和CO2;另一方面植物根际可促进有机污染物的根际生物吸收与,使植物对有机污染环境的修复效果更明显。文中探讨了有机污染环境的植物修复技术的优势、问题与未来的研究。     

高氯酸盐污染及修复的研究进展

戏真做高氯酸盐作为一种甲状腺干扰物质,因其高溶解度、低吸附性及其稳定性,决定了其是一种可快速扩散的持久型污染物,其环境污染问题已引起人们的高度关注。从高氯酸盐污染的危害性出发,阐述了我国可能存在的高氯酸盐污染状况,并对近年来不同介质中高氯酸盐的分析检测技术及前处理方法进行了介绍,同时对已开展的高氯酸盐动物毒理研究、在不同环境介质中的迁移转化和植物积累、及其按生物修复和非生物修复进行分类的修复方法进行了综述。最后,对进一步研究的意义和方向提出建议。     

环境中污染物降解基因的水平转移(HGT)及其在生物修复中的作用

水平基因转移是不同于垂直基因转移的遗传物质的交流方式.在污染环境这一特异生态环境中,降解基因的水平转移有着独特的功能与作用.研究环境中污染物降解基因在微生物间的水平转移,更深入地了解微生物种群适应污染环境的机理,对于评价污染物的环境毒理、生物可降解性以及污染环境的可修复潜力具有重要参考价值.在污染物生物修复实践中,可以通过调控降解基因的水平转移,增强污染环境中微生物的降解能力,更有效地发挥生物修复作用.文章将对环境中细菌间基因交流的机制,污染物降解基因的水平转移对微生物适应污染环境的机理、水平基因转移对代谢途径的进化及其对污染物生物修复作用的影响等方面的研究进展做一综述.     

嗜盐微生物在环境修复中的研究进展

人类活动产生的污染物,使一些天然盐环境遭受不同程度的污染,或者使环境受到污染物与高盐的双重污染。在高盐条件下,非嗜盐微生物的代谢会受到抑制,其生物修复效率明显降低,甚至丧失修复能力。嗜盐微生物则能够在高盐环境中栖息繁殖,凸显其修复被污染高盐环境的生物学效率和广阔的应用前景。就嗜盐微生物降解石油烃、芳香烃衍生物和有机磷等污染物的研究进展进行了综述和讨论。     

内生菌协同宿主植物修复土壤复合污染的研究进展

土壤复合污染日益严重,危及植物生长及人类发展,寻找修复土壤复合污染的有效方法已经成为环境领域的优先事项。复合污染指同一环境中存在两种或两种以上的污染物,分为复合重金属污染、复合有机污染物污染及重金属-有机污染物复合污染。近些年发现内生菌能定殖在植物中,并且被感染的植物不会引起任何外在病症,其主要通过促进宿主植物生长,改变植物摄取污染物能力和酶促降解污染物等方法增强植物修复能力。本文综述了具有复合重金属和复合有机污染抗性的内生菌种类及其作用机制,并展望了内生菌协同宿主植物修复环境中复合污染物的研究方向。     

海洋石油污染物的微生物降解与生物修复

石油是海洋环境的主要污染物 ,已经对海洋及近岸环境造成了严重的危害。微生物降解是海洋石油污染去除的主要途径。海洋石油污染物的微生物降解受石油组分与理化性质、环境条件以及微生物群落组成等多方面因素的制约 ,N和P营养的缺乏是海洋石油污染物生物降解的主要限制因子。在生物降解研究基础上发展起来的生物修复技术在海洋石油污染治理中发展潜力巨大 ,并且取得了一系列成果。介绍了海洋中石油污染物的来源、转化过程、降解机理、影响生物降解因素及生物修复技术等方面内容 ,强调了生物修复技术在治理海洋石油污染环境中的优势和重要性 ,指出目前生物修复技术存在的问题。     

微生物降解持久性有机污染物的研究进展与展望

持久性有机污染物（POPs）是伴随着人类工业化发展而产生的合成类污染物,具有高毒性、持久性、长迁移性和高生物富集性等特点,POPs污染物的微生物降解一直是环境科学与技术应用领域的研究热点。微生物降解技术修复POPs污染环境具有无二次污染、成本低、快速简便等优点,拥有广泛的应用前景。本文论述了各种POPs微生物分解代谢的最新研究进展,包括降解性微生物资源以及降解机制。此外,还讨论了计算生物学、合成生物学、基因组学等技术在POPs微生物降解中的潜力和应用,以期为环境中持久性有机污染物的修复提供参考。     

多环芳烃污染生物修复研究进展

多环芳烃(polycyclic aromatic hydrocarbon,PAHs)是一类对环境有严重危害的持久性有机污染物。具有高生物富集性、致癌性、致毒性和难降解性,修复治理PAHs污染环境备受国内外政府及学者的关注。目前主要采用物理、化学以及生物方法对多环芳烃污染的土壤和水体进行修复。其中生物修复是一种高效、经济和生态可承受的环保技术,具有成本低、无二次污染等优点。本文从植物修复、微生物修复以及植物-微生物联合修复方面,阐述了国内外生物修复PAHs污染的最新研究进展。指出了生物修复PAHs污染环境需要进一步解决的问题,并对未来发展趋势进行了展望。     

放射性核素在森林生态系统中的迁移规律及核污染土地的利用

放射性核素常危及生态系统的稳定,给人类的生命和健康带来巨大的威胁。森林生态系统具有独特的特点和功能,利用其修复放射性污染的土壤具有重要的意义。本文就森林生态系统对放射性核素的截持、保持、放射性核素在森林生态系统中的移动规律以及森林生态系统对放射性核素污染土壤的修复进行了探讨。     

Microbial mats for multiple applications in aquaculture and bioremediation

Microbial mats occur in nature as stratified communities of cyanobacteria and bacteria, but they can be cultured on large-scale and manipulated for a variety of functions. They are complex systems, but require few external inputs. The functional uses of mats broadly cover the areas of aquaculture and bioremediation. Preliminary research also points to promising uses in agriculture and energy production. Regarding aquaculture, mats were shown to produce protein, via nitrogen fixation, and were capable of supplying nutrition to tilapia (Oreochromis niloticus). Current research is examining the role of mats in the nitrification of nutrient-enriched effluents from aquaculture. Most research has addressed bioremediation, within which two majors categories of contaminants were examined: metals and radionuclides, and organic contaminants. Mats sequester or precipitate metals/radionuclides by surface absorption or by conditioning the surrounding chemical environment, thus bioconcentrating the metal/radionuclide in a small volume. Organic contaminants are degraded and may be completely mineralized. For agriculture mats hold promise as a soil amendment and nitrogen fertilizer. The use of mats in biohydrogen production has been verified, but is in a preliminary phase of development. We propose a comprehensive closed system based on microbial mats for aquaculture and waste management.     

Fungi and ionizing radiation from radionuclides

Radionuclides in the environment are one of the major concerns to human health and ecotoxicology. The explosion at the Chernobyl nuclear power plant renewed interest in the role played by fungi in mediating radionuclide movement in ecosystems. As a result of these studies, our knowledge of the importance of fungi, especially in their mycorrhizal habit, in long-term accumulation of radionuclides, transfer up the food chain and regulation of accumulation by their host plants was increased. Micro-fungi have been found to be highly resilient to exposure to ionizing radiation, with fungi having been isolated from within and around the Chernobyl plant. Radioresistance of some fungal species has been linked to the presence of melanin, which has been shown to have emerging properties of acting as an energy transporter for metabolism and has been implicated in enhancing hyphal growth and directed growth of sensitized hyphae towards sources of radiation. Using this recently acquired knowledge, we may be in a better position to suggest the use of fungi in bioremediation of radioactively contaminated sites and cleanup of industrial effluent.     

Microbial interaction with and tolerance of radionuclides: underlying mechanisms and biotechnological applications

Radionuclides (RNs) generated by nuclear and civil industries are released in natural ecosystems and may have a hazardous impact on human health and the environment. RN-polluted environments harbour different microbial species that become highly tolerant of these elements through mechanisms including biosorption, biotransformation, biomineralization and intracellular accumulation. Such microbial–RN interaction processes hold biotechnological potential for the design of bioremediation strategies to deal with several contamination problems. This paper, with its multidisciplinary approach, provides a state-of-the-art review of most research endeavours aimed to elucidate how microbes deal with radionuclides and how they tolerate ionizing radiations. In addition, the most recent findings related to new biotechnological applications of microbes in the bioremediation of radionuclides and in the long-term disposal of nuclear wastes are described and discussed.     

The investigation of the composition of liquid radioactive waste

In investigation the process of composition sediment of liquid unorganic radioactive waste, that are forming in cistern-selectors at PNPI RAS, it was discovered apart from great quantity of ions of different metals and radionuclides considerable maintenance of organic material (to 30% and more from volume of sediment) unknown origin. A supposition was made about its microbiological origin. Investigation shows, that the main microorganisms, setting this sediment, are the bacterious of Pseudomonas kind, capable of effectively bind in process of grow the radionuclide 90Sr, that confirms the potential posibility of using this microorganisms for bioremediation of liquid low radioactive wastes (LRW).     

Teratogenic effects of incorporated radionuclides

Experimental data on teratogenic effects induced by incorporated alpha, beta and gamma-emitters were analyzed. It was found that the radioactive substances as well as external irradiation induced teratogenic effects. Teratogenesis caused by incorporated radionuclides has some peculiarities compared to the effect caused by fetus exposure to external radiation. These peculiarities are related to the fact of the limited penetration of incorporated radionuclides via placenta barrier so the radiation fetal doses are accumulated within long period of time and radiation dose rates are relatively low. The exposure to incorporated radionuclides does not induce severe developmental defects. Most frequent developmental defects of fetus include its death, general retardation of the development and growth. In such case the earlier pregnancy term was affected by radionuclide the more severe fetal damages occur in fetus because of the gradual increase of absorbed dose even in case of single intake of radionuclide. RBEs of radionuclides if compared to that for external gamma radiation are evaluated as follows: 2-4 (tritium oxide), 20 (241Am), 50 (238Pu) and 3-5 (131I in thyroid).     

Genotoxicity and toxicity assay of water sampled from the underground nuclear explosion site in the north of the Perm region (Russia)

The results of our study revealed a local biologically relevant surface water contamination in the radionuclide anomaly in the north of Russia (Perm region) by means of Allium shoenoprasum L. the anaphase-telophase chromosome aberration assay. This radionuclide anomaly was formed in 1971 as a result of an underground nuclear explosion with soil excavation. Specific activities of main dose-forming radionuclides in all examined reservoirs are below intervention levels officially adopted in Russia for drinking water. We found that 90Sr significantly contribute to induction of cytogenetic disturbances. Our previous and described here data suggest that metal ions and radionuclides combined exposure on the various biota species (with the dose below permissible exposure limits for human) may cause substantial biological effects in part be due to synergic response. The findings described here indicated that development of a new concept of radiation protection for humans and biota should be based on the clear understanding of biological effects of low doses of radiation in chronic exposure to multi-pollutant mixtures.     

Naturally occurring radionuclides in food and drinking water from a thorium-rich area

This paper focuses on a survey of uranium and thorium decay chain radionuclides in food and drinking water from the thorium-rich (monazite-bearing) region of Buena, which is located in the state of Rio de Janeiro, Brazil. The radionuclide concentration values in the food and drinking water from Buena reached values higher than 100-fold the international reference values. The daily intake of radionuclides by the local population is similar to that of another high background radiation area in Brazil, but the intake is higher than that of residents from a normal background radiation area. Approximately 58?% of the food consumed by Buena inhabitants is produced locally. Based on that figure, locally produced food and the dilution of total radionuclides in the diet of residents caused by food importation are both highly relevant to a population’s intake of radionuclides. The concentration values for ²¹⁰Pb and the radium isotopes in drinking water from Buena are among the highest values to be reported in the literature. ²²⁸Ra is the most important radionuclide ingested with both food and water among the inhabitants of Buena.     

Considerations on the behavior of long-lived radionuclides in the soil

The migration of radionuclides from waste repositories to the biosphere potentially leads to a contamination of soil. Due to the importance of food production, the mobilisation and accumulation behaviour of long-lived radionuclides in the soil plays a key role in performance assessment studies. In this paper, the main features and processes that control radionuclide behaviour in soil, such as pH, redox potential and sorption to organic and inorganic soil components, are discussed for the radionuclides ³⁶Cl, ⁷⁹Se, ¹²⁹I, ⁹⁹Tc, ²³⁷Np and ²³⁸U, that are usually most relevant in long-term safety assessments of nuclear waste. The interaction of radionuclide behaviour in soil with environmental factors, such as temperature and humidity as well as farming practices are discussed. The possible impact of future soil development on long-term behaviour in soil are taken into consideration. Due to the physiological constraints of plant growth, appropriate soil conditions for growth will probably not be substantially different from current requirements, bearing in mind that sustainable agriculture strives for optimal plant growth. Against this background, present-day parameters may in general be considered appropriate for roughly estimating the behaviour of radionuclides in the soil-plant system. Received: 18 October 2000 / Accepted: 20 March 2001     

The Impact of Fe(III)-reducing Bacteria on Uranium Mobility

The ability of specialist prokaryotes to couple the oxidation of organic compounds to the reduction of Fe(III) is widespread in the subsurface. Here microbial Fe(III) reduction can have a great impact on sediment geochemistry, affecting the minerals in the subsurface, the cycling of organic compounds and the mobility of a wide range of toxic metals and radionuclides. The contamination of the environment with radioactive waste is a major concern worldwide, and this review focuses on the mechanisms by which Fe(III)-reducing bacteria can affect the solubility and mobility of one of the most common radionuclide contaminants in the subsurface, uranium. In addition to discussing how these processes underpin natural biogeochemical cycles, we also discuss how these microbial activities can be harnessed for the bioremediation of uranium-contaminated environments.