EXPERIMENTS ON AQUATIC ECOSYSTEM REGIME SHIFT IN ENCLOSURES NEAR LAKE DIANCHI, CHINA

To discover how a lake converts from a turbid state to clean state, and what drives this process, we constructed controlled enclosure ecosystems and used the ecological remediation method to force ecosystems to convert from the turbid state to the clean state. Our results show that the driving forces include temperature., macrophyte, silver carp and mussel, which form a combined force to drive the controlled ecosystem to switch. There is a threshold existing in treated enclosure ecosystem during the conversion from turbid to clean state. When TP <0.09 mg.L-1, Chl-a <0.036 mg.L-1, transparency >62 cm, TN <2.15 mg.L-1, CODMn <13.7 mg.L-1, tubidity <10, and the number of algal cells <10(6) cells.L-1, the treated ecosystem changes sharply from turbid to clean state. The conversion process can be divided into three phases: turbid state, clean-turbid transitional state as well as clean state, and described with the power function Y = a*X-b (where Y is water parameter, X is time, a and b are constants), which indicates that the shift in the enclosure ecosystem from turbid to clean state is discontinuous.

Phytoremediation of triazophos by Canna indica Linn. in a hydroponic system

The phytoremediation of triazophos (O, O-diethyl-O-(1-phenyl-1, 2, 4-triazole-3-base) sulfur phosphate, TAP) by Canna indica Linn. in a hydroponic system was studied. After 21 d of exposure, the removal kinetic constant (K) of TAP was 0.0229-0.0339 d(-1) and the removal percentage of TAP was 41-55% in the plant system and the K and removal percentage of TAP were about 0.002 d(-1) and 1%, respectively, in darkness and disinfected control. However, the K and removal percentage of TAP were 0.006 d(-1) and approximately 11%, respectively, in the treatment with eluate from the media of constructed wetland. The contribution of plant to the remediation of TAP was 74% and C. indica played the most important role in the hydroponic system. Under the stress of TAP and without inorganic phosphorus nutrient, the activity of phosphatase in the plant system increased and phytodegradation was observed. The production and release of phosphatase is seen as the key mechanism for C. indica to degrade TAP. C. indica, which showed the potential of phytoremediation of TAP, and is commonly used in constructed wetland, so the technique of phytoremediation of TAP from contaminated water can be developed with the combination of constructed wetland.

Man-made desert algal crusts as affected by environmental factors in Inner Mongolia, China

Man-made desert algal crusts were constructed on a large scale (3000m(2)) in Inner Mongolia, China. Microcoleus vaginatus was mass cultivated and inoculated directly onto unconsolidated sand dune and irrigated by automatic sprinkling micro-irrigation facilities. The crusts were formed in a short time and could resist the erosion of winds and rainfalls 22 days after inoculation. The maximum biomass in the man-made algal crusts could also reach 35 mu g Chl a/cm(2) of soil. Effects of environmental factors such as temperature, irrigation, rainfall and soil nutrients on algal biomass of man-made algal crusts were also studied. It was found that rainfalls and lower light intensity had significantly positive effects on the biomass of man-made algal crusts. The preliminary results suggested that man-made algal crusts could be formed rapidly, and thus it might be a new feasible alternative method for fixing unconsolidated sand. (c) 2006 Elsevier Ltd. All rights reserved.

Development of low-pH cements for immobilisation of intermediate level radioactive waste: Achievements and challenges

Although cementation is a widely recognized solidification/ stabilization process for immobilisation of Intermediate Level Radioactive Waste (ILRW), the low resistance to hyperalkaline pore waters compromises the effectiveness of the process when Portland Cement (PC) is employed. Moreover the manufacture of PC is responsible for significant CO2 emissions. In this context, low pH cements are environmentally more suitable and have emerged as a potential alternative for obtaining secure waste forms. This paper summarises the achievements on development of low-pH cements and the challenges of using these new materials for the ILRW immobilisation. The performance of waste forms is also discussed in terms of radionuclides release. Reactive magnesium oxide and magnesium phosphate cements are emphasised as they feature important advantages such as consumption of available constituents for controlling acid-base reactions, reduced permeability and higher density. Additionally, in order to identify new opportunities for study, the long-term modelling approach is also briefly discussed. Copyright © 2013 by ASME.

Effects of heavy metals on plants and resistance mechanisms

Goal, Scope and Background. As one of the consequences of heavy metal pollution in soil, water and air, plants are contaminated by heavy metals in some parts of China. To understand the effects of heavy metals upon plants and the resistance mechanisms, would make it possible to use plants for cleaning and remediating heavy metal-polluted sites. Methods. The research results on the effects of heavy metals on plants and resistant mechanisms are compiled from Chinese publications from scientific journals and university journals, mostly published during the last decade. Results and Discussion. Effects of heavy metals on plants result in growth inhibition, structure damage, a decline of physiological and biochemical activities as well as of the function of plants. The effects and bioavailability of heavy metals depend on many factors, such as environmental conditions, pH, species of element, organic substances of the media and fertilization, plant species. But, there are also studies on plant resistance mechanisms to protect plants against the toxic effects of heavy metals such as combining heavy metals by proteins and expressing of detoxifying enzyme and nucleic acid, these mechanisms are integrated to protect the plants against injury by heavy metals. Conclusions. There are two aspects on the interaction of plants and heavy metals. On one hand, heavy metals show negative effects on plants. On the other hand, plants have their own resistance mechanisms against toxic effects and for detoxifying heavy metal pollution. Recommendations and Outlook. To study the effects of heavy metals on plants and mechanisms of resistance, one must select crop cultivars and/or plants for removing heavy metals from soil and water. More highly resistant plants can be selected especially for a remediation of the pollution site. The molecular mechanisms of resistance of plants to heavy metals should be studied further to develop the actual resistance of these plants to heavy metals. Understanding the bioavailability of heavy metals is advantageous for plant cultivation and phytoremediation. Decrease in the bioavailability to farmlands would reduce the accumulation of heavy metals in food. Alternatively, one could increase the bioavailability of plants to extract more heavy metals.

铬污染土壤修复过程中土壤细菌群落多样性的RFLP分析

对污染土壤修复过程中土壤细菌群落多样性的变化进行研究。【方法】以淹水培养后的模拟铬污染土壤为供试材料,通过直接提取土壤中总细菌DNA,利用细菌专一引物克隆细菌16S rDNA片段,分别建立克隆文库。利用PCR-RFLP技术,分析比较了土壤淹水10 d(对照,S1)、添加Cr(Ⅵ)淹水10 d(S2)、添加Cr(Ⅵ)和Fe(OH)3淹水10 d(S3)及20 d(S4)4个处理中土壤细菌群落的变化。【结果】用专一引物克隆细菌16S rDNA片段,分别建立了克隆文库;用限制性内切酶RsaⅠ进行细菌16S rDNA PCR-RFLP分析,分别得到123,120,97和69个酶切类型,库容值分别为54.92%,55.43%,65.33%和76.60%;Shannon-Wiener指数、Gini指数、物种丰富度指数(dMa)和物种均匀度指数(Jgi)均表现为S1>S2>S3>S4,以上4个指数的变异系数分别为11.51%,1.84%,23.64%和1.55%;基于细菌多样性参数的聚类分析结果,将对照S1和添加Cr(Ⅵ)处理的S2归于一类,而2个添加Fe处理的土壤S3和S4聚为一类。【结论】经过10 d淹水处理,...

超积累观赏植物筛选及生态修复强化技术研究

近年来，我国土壤的重金属污染形势日益严峻，大量的重金属污染土壤亟待修复。而重金属污染土壤的植物修复技术已受到人们的普遍重视，将观赏植物应用于污染土壤修复方面的研究刚刚兴起，就已展现出巨大的发展潜力。本研究针对土壤重金属镉（Cd）、砷（As）严重污染的局面，以及目前发现的超积累观赏植物种类极少和修复能力有限的现状，通过模拟实验筛选方法，以观赏植物作为研究对象，力图从中筛选出Cd/As超积累植物；同时将施肥强化措施和络合强化技术联合使用，以提高观赏植物修复Cd污染土壤的效率，降低修复成本和可能造成的环境风险。 通过盆栽实验初步分析了18种观赏植物对Cd、As的耐性和积累特征，根据超积累植物应具备的4个基本特征，从中挑选出孔雀草、缨绒花、雏菊3种具备Cd超积累特征的潜力植物，并发现所有参试植物均不具备As超积累特征。 通过盆栽梯度实验、污染小区实验以及水培梯度实验进一步研究了3种潜力植物在不同生长环境中对Cd的耐性和积累特征。结果表明，孔雀草和缨绒花是Cd超积累植物，在一定Cd污染范围内，两种植物地上部Cd含量均达到了Cd超积累植物的临界含量标准，地上部Cd含量高于根部和土壤中Cd含量，且对Cd污染的耐性较强，完全符合Cd超积累植物的基本特征。而雏菊不是Cd超积累植物，只是一种具备部分超积累特征的Cd富集植物。 生态修复强化实验表明，铵态氮肥(NH4)2SO4和螯合剂EGTA的联合强化处理，不仅可以有效缓解螯合剂对植物的毒害，显著提高植物地上部生物量，还可以增强螯合剂促进植物吸收累积Cd的作用，最终大幅提高了孔雀草修复Cd污染土壤的效率，使其明显高于相同和加倍剂量的螯合剂处理。因此，基于铵态氮肥与螯合剂联合使用的强化修复措施，既提高了修复效率，又减少了螯合剂用量，从而降低了修复成本和环境风险，是一种高效、安全的生态修复强化措施。

多氯联苯污染土壤的钯/铁双金属还原和生物降解联合修复研究

本文以土壤为介质，以2,4,4′-三氯联苯、2,2′,5,5′-四氯联苯、2,2′4,5,5′-五氯联苯、2,2′,3,4,4′,5-六氯联苯和2,2′,3,4,4′,5,5′-七氯联苯为目标污染物，对钯/铁双金属、微生物及其联合修复多氯联苯污染土壤进行了研究。 对钯/铁双金属还原脱氯多氯联苯的影响因素和动力学进行了研究，研究结果表明：较高的钯化率、反应温度，弱酸性pH条件对脱氯反应有促进作用；在实验所考察的初始浓度范围内，脱氯效果与多氯联苯的初始浓度关系较小；而钯/铁双金属投加量则存在一个适宜值，不宜太高或太低。多氯联苯催化脱氯符合准一级反应动力学。反应速率与多氯联苯初始浓度关系很小；反应速率随钯化率、钯/铁投加量和反应温度升高而增大；初始pH为5.5时反应速率最快。且联苯环上氯取代数越少，越难以脱氯。 从受多氯联苯长期污染的土样中筛选出一株高效降解多氯联苯的细菌（H1），菌株初步鉴定为芽胞杆菌属。在本实验条件下，微生物对土壤中多氯联苯的降解较为适宜的条件为：微生物接种量10%、反应温度在30℃左右、pH在7左右。在此条件下，微生物对PCBs的降解，随初始浓度的增加，降解速率逐渐降；且随氯取代数目的增加，降解率逐渐降低。 采用化学和微生物方法联合修复多氯联苯污染土壤是可行的。经过钯/铁双金属和好氧微生物连续处理后，2,4,4′-三氯联苯和2,2′,5,5′-四氯联苯几乎被完全降解，而2,2′4,5,5′-五氯联苯、2,2′,3,4,4′,5-六氯联苯和2,2′,3,4,4′,5,5′-七氯联苯还原脱氯后生成的低氯代同系物（2,2′,5-三氯联苯）也很容易被微生物所降解。 利用GC-MS对多氯联苯的中间产物及最终产物的分析，推测多氯联苯降解的反应机理为：在钯/铁双金属——水体系中，铁作为还原剂给出电子，水为质子供体。在催化剂钯作用下，H+与铁给出的电子在双金属表面结合，形成具有高反应活性的中间产物——新生态H*。H *攻击多氯联苯取代联苯环上的氯形成脱氯产物和氯离子。反应体系中的溶解氧与溶解铁结合在钯/铁表面形成氧化层，阻碍反应进行。过多的H2气泡也会覆盖活性反应位，对脱氯反应不利。

辽河流域复合污染底泥的生物-化学联合修复研究

辽河流域工业历史长，污染负荷大，大量污染物随废水排放沉积于河道底泥，成为二次污染源。对污染底泥进行修复，对保障水质安全、实现人与自然和谐发展具有重大意义。本研究针对辽河流域污染状况，开展了微生物与零价铁两种方式联合修复氯代烃、多环芳烃、重金属污染底泥的研究；并采用PCR-DGGE和PLFA两种分析技术相结合，研究了零价铁修复对底泥微生物群落结构的影响。 研究结果表明：①利用水-硅油双相系统从污染底泥中筛选得到3株三氯乙烯降解菌WT1、FT10、FT17，经鉴定分别为Achromobacter xylosoxidans、Sporosarcina aquimarina、Sporosarcina ginsengisoli。在5mg•L-1三氯乙烯作为单一基质的情况下，3天后的降解率分别为：53.4%、48.1%、44.6%。500 mg•L-1乙酸钠和乳酸钠作为共代谢基质均可以促进菌株WT1对三氯乙烯的去除。全细胞蛋白图谱分析表明，乙酸钠和三氯乙烯共同诱导菌株WT1表达了一条分子量约为59kDa的新蛋白带，可能与三氯乙烯降解有关。②零价铁对底泥三氯乙烯、1，3-二氯苯、菲、芘、Cr(Ⅵ)污染具有较好的去除作用，土著微生物也能促进上述污染物的去除，但是去除效果不及零价铁明显。③正交实验结果表明：零价铁粒径对三氯乙烯、1，3-二氯苯、Cr(Ⅵ)污染底泥修复有显著影响；初始pH值越低，温度越高，粒径越小，添加量越大，零价铁对污染物的去除效率就越高。④DGGE和PLFA分析结果表明：零价铁修复使污染底泥中耐受菌群减少，敏感菌群重新出现，使部分污染底泥微生物的多样性、磷脂脂肪酸含量、特定微生物类群和环境压力恢复至未污染对照水平，表明零价铁修复有利于污染底泥微生物群落结构的恢复。

芘降解菌在石油污染土壤修复过程中的代谢调控

沈抚灌区是我国面积最大、污灌历史最长的石油类污水灌溉区，土壤中大分子量多环芳烃污染严重，对当地粮食生产与生态安全造成严重危害。对此类污染土壤进行生物修复，对保证农产品的安全，实现当地人与自然的可持续发展具有重大的意义。 本研究以沈抚灌区污染土壤中大分子多环芳烃芘为主要研究对象，采用稳定同位素比率分析技术（IRMS），以磷脂脂肪酸（PLFA）为生物标记物，分析污染土壤参与芘降解的优势微生物类群；并以此为指导，采用分子生物学手段和传统微生物学分析方法，筛选土壤中的高效降解菌，并追踪其释放到土壤中后的动态变化与调控。 从沈抚灌区土壤富集培养芘的降解菌，经过双层平板法初筛和芘降解菌液体摇瓶复筛，获得5株以芘为唯一碳源生长的具有较高降解活性菌株。 将筛选的降解菌投加到污染土壤中，以13C标记的芘为代谢底物，以土壤微生物的磷脂脂肪酸为生物标记物，采用稳定同位素比率分析方法(GC-C-IRMs)，分析投加的降解菌在原位土壤中的降解作用。结果显示，与不加菌的对照土壤相比，富含13C的磷脂脂肪酸指纹图谱相似度较高的为投加了菌株B05和菌株B15的土壤，芘的降解效率也最高，表明这两株菌在原位土壤芘降解中发挥了重要作用。根据形态学观察、16项生理生化鉴定和16S rDNA序列分析结果，将菌株B05鉴定为 Aminobacter ciceronei，将菌株B15鉴定为 Microbacterium arabinogalactanolyticum。菌株B05初步确定为一株新的芘降解菌，并对菌株培养条件进行了优化。 采用PCR-DGGE方法，研究了筛选的5株降解菌在不同的营养条件下释放到土壤中后的数量和代谢活性的变化。PCR-DGGE图谱分析表明：投加初期外加菌在竞争中占据优势，但是随时间推移，营养物质的消耗，优势逐渐消失，PCR-DGGE的条带趋向于一致。菌株B05的稳定期相对较长，在DGGE图谱中的条带相对密度大，而且对芘的降解率最高，是一株具有潜在应用价值的高效降解菌。混合菌比单一菌降解率高，添加碳氮源有利于外加菌群更快更好的适应在污染土壤中生存，而且有助于对多环芳烃的降解。

用植物油淋洗修复多环芳烃污染土壤

研究用植物油淋洗修复多环芳烃污染土壤的效果、植物油淋洗剂再生与回用的可行性、植物油的生态效应。采用了批处理法和土柱法对多环芳烃污染土壤进行修复，结果表明：油土比1：1的条件下，批处理法可以去除土壤中90％以上的多环芳烃，多环芳烃的质量转移过程可以用经验模型模拟。恰当的运行条件下，土柱法可去除土壤中90％以上的多环芳烃，但是根据土壤中多环芳烃浓度的高低，植物油的用量是批处理法的2～4倍。无论是批处理法，还是土柱法，土壤水分含量都影响了植物油去除土壤中多环芳烃的能力。采用了化学氧化法、溶剂提取法和吸收剂吸收法对植物油进行再生，结果表明：臭氧和双氧水能氧化植物油中的多环芳烃，但不理想，紫外线及双氧水在pH＝3的条件下可氧化植物油中76.5％的多环芳烃。按植物油／乙醇1:3的比例对植物油进行6级处理可氧化植物油中87％的多环芳烃。活性炭二级处理可去除植物油中87％的多环芳烃，实现植物油的再生。高等植物生长实验说明土壤中的植物油对燕麦及萝卜的生长起了抑制作用，土壤呼吸实验证明，残留在土壤中的植物油可被生物降解，但是必须保证良好的氧气及营养供应。用植物油修复多环芳烃污染土壤具有可行性。

花卉植物在污染土壤修复中的资源潜力分析

通过对14种草本花卉在Cd、Cd-Pb、Cd-Pb-柴油、Cd-甲胺磷等单一与复合污染条件下的耐性及重金属积累特性研究，就这些花卉对污染土壤修复的资源潜力有了大致的认识，为污染环境的生态修复及其集成技术的创新与应用提供了科学依据，同时也提供了具有我国自主知识产权的污染土壤修复材料的基本信息。通过盆栽实验，发现黄蜀葵、醉蝶、金盏菊、凤仙、蜀葵和紫茉莉六种植物对Cd单一污染表现出较强的耐性，约占参试花卉种的43％，说明花卉植物较有耐重余属的潜力。金盏菊在实验浓度下，地上部富集系数大于1且地上部的Cd含量大于根部含量，表现出重金属超积累植物的基本特征，但在本试验条件下还没有达到100mgkg-1Cd的超积累植物临界含量特征，因此，有待进一步实验证实。熔液培养条件下，黄蜀葵、紫茉莉、凤仙、万寿菊、串红五种花卉种子发芽对Cd表现为较强的耐性，因为其种子发芽率在Cd污染暴露条件下无明显影响（p＞0.05）。但是，Cd对这五种花卉幼苗期根伸长的影响较为显著（p＜0.05），并且Cd与花卉植物的幼苗期根长抑制之间存在线性相关关系。在复合污染条件下（Cd-Pb，Cd-Pb-柴油），14种参试花卉种，除金鸡菊和观赏向曰葵两种花卉表现出生物量明显（P＜0.05）下降，即对重金属复合污染耐性较弱外，其余12种表现出对复合污染有较强的耐性。黄蜀葵在Cd一甲胺磷联合作用下的耐性研究表明，Cd与甲胺磷对黄蜀葵且对幼苗期根伸长的影响较发芽的影响大。对Cd与甲胺磷的联合效应分析表明Cd和甲胺磷存在拮抗作用，同时这种联合作用则是更多地依赖于Cd而非甲胺磷。

Metabolic studies on the nitrophile yeast Rhodotorula glutinis DSBCA06

Nitrogen is the most abundant element in atmosphere and fundamental component of proteins, nucleic acids and other essential molecules. In the past century the industrial use of nitrogen compounds has grown exponentially causing widespread pollution. Nitrogen pollution has wide-ranging impacts including contributions to global warming, acid rains and eutrophication. Reduction of nitrogen use in industry and agriculture coupled whit remediation treatments could represent a solution. To this purpose we isolated from environmental samples a nitrophile strain capable of removing nitrogen compounds efficiently from the medium. Through the molecular characterization, we identified the strain as a Rhodotorula glutinis that we called DSBCA06. We examined the main metabolic features of the strain, also to determine the best growing conditions. At the same time, the ability of the strain to grow in presence of high nitrite concentrations was assayed, being a relevant feature poorly studied earlierfor other environmental yeasts. The ability of the strain to grow in presence of heavy metal cations was also tested, showing a noticeable tolerance. The cost of bioremediation treatments is often a problem. One of the way to obviate this is to produce valuable secondary metabolites, capable of positively impact the cost of the processes. In this context the ability of the strain to produce carotenoids, natural molecules with antioxidant properties used for food production, cosmetic and pharmaceutical industry, has been evaluated. The strain Rhodotorula glutinis DSBCA06 showed interesting features suggesting its possible use in bioremediation or industrials process for production of secondary metabolites such as lipids and carotenoids.

Biomimetic emulators of high potential peroxygenases: Implications in bioremediation and metabolic studies

Nowadays, classical (bio)remediation processes are affected by some economical and environmental drawbacks. These approaches often seem to be inadequate, particularly in the perspective of sustainable green processes. Since immobilized metalloporphines can emulate the active site of peroxidases and peroxygenases, their use in several bioremediation processes has been analyzed in this work. The described catalytic reactions use bioinspired, homogenized or heterogenized, commercial porphines and showed a remarkable ability to catalyze substrates oxidation at the expenses of different oxidants such as Oxone and hydrogen peroxide. The biomimetic catalysts have been also investigated about their peroxidase- and peroxygenase-like catalysis and ability to emulate lignolytic peroxidases action and substrate specificity. The adducts showed a remarkable ability to catalyze veratryl alcohol (widely recognized as a simple model compound of lignin) oxidation at the expenses of H2O2. In the perspective of broadening industrial applications of the described catalysts, the oxidation of several pollutants such as durable textile dyes and inorganic sulfides, has been attempted with quite promising results, and some findings open the way toward industrial scaling-up. Accordingly, the inexpensiveness of the synthesis and the mild operational conditions allow these adducts to be proposed as applicable catalysts also for industrial large-scale processes. Besides, these synthetic models are helpful also to understand the behavior of pharmaceuticals, antifungal drugs in this case, in the environment, and to predict the drug metabolism by cytochromes P450. The biomimetic catalysts, for the studied cases, also proved to be much more efficient than the corresponding enzymes.