EDTA对Cu参水生微宇宙中的毒性和分布的影响

利用实验人工合成培养微宇宙,研究了不同浓度ＥＤＴＡ对微宇宙中Ｃｕ的毒性及Ｃｕ的分布,结果表明,在微宇宙运行过程中,投加２．９ｍｇ·Ｌ＾－１Ｃｕ后,ＥＤＴＡ浓度为０．０ｍｇ·Ｌ＾Ｓ－１试验组中大型溲种群大小、叶绿素ａ浓度及总初级生产力与总呼吸的比值（Ｐ／Ｒ）随时间变动曲线,明显低于其它试验组的曲线,ＥＤＴＡ的存在削弱了Ｃｕ对大型溲和藻类的毒性作用,并缓解了Ｃｕ对生态系统代谢功能的干扰;同时改变了微宇     

人工微宇宙下粘细菌捕食对微生物群落结构的影响

【目的】人工微宇宙条件下测试粘细菌捕食对微生物群落结构的影响,模拟粘细菌捕食对微生态系统的调控作用。【方法】采用Lawn predation法,测定粘细菌EGB对9种猎物菌的捕食直径,以确定其对猎物菌的捕食能力。通过高通量测序技术分析粘细菌捕食引起的微生物群落结构变化。【结果】粘细菌EGB对9种不同猎物菌的捕食能力差异显著,粘细菌对热带芽孢杆菌的捕食能力显著高于其他细菌(P<0.05)。在含有9种猎物细菌的人工微宇宙系统中添加不等量粘细菌,均可显著降低细菌群落的多样性指数(Shannon)。PCoA结果表明粘细菌捕食可影响微宇宙微生物群落结构。人工微宇宙培养24 h后,7种猎物菌相对丰度显著降低(LefSe,P<0.05),但洋葱伯克霍尔德菌的相对丰度显著升高(P<0.05)。人工微宇宙实验的结果表明,粘细菌添加是造成其微生物群落结构改变的主要影响因素,且添加最小剂量的粘细菌(1 mL)也有显著的影响效果;随着培养时间的增加,洋葱伯克霍尔德菌是唯一能抵抗粘细菌捕食并具有较高丰度的猎物细菌。【结论】粘细菌捕食能够调控微宇宙中微生物的群落结构,为其对土壤生态的调控研究奠定了理论基础。     

EDTA对Cu在水生微宇宙中的毒性和分布的影响

利用实验室人工合成培养微宇宙,研究不同浓度ＥＤＴＡ（０．０、１．０、８．０ｍｇ·Ｌ－１）对微宇宙中Ｃｕ（２．０ｍｇ·Ｌ－１）的毒性及Ｃｕ的分布．结果表明,在微宇宙运行过程中,投加２．０ｍｇ·Ｌ－１Ｃｕ后,ＥＤＴＡ浓度为０．０ｍｇ·Ｌ－１试验组中大型种群大小、叶绿素ａ浓度及总初级生产力与总呼吸的比值（Ｐ／Ｒ）随时间变动曲线,明显低于其它试验组的曲线,ＥＤＴＡ的存在削弱了Ｃｕ对大型和藻类的毒性作用,并缓解了Ｃｕ对生态系统代谢功能的干扰;同时改变了微宇宙中Ｃｕ在不同隔室中的分布,水体中Ｃｕ相对增加（０．１％～６．７％）,沉积物中相对减少（０．８％～６．５％）;ＥＤＴＡ的存在影响了藻类和大型对Ｃｕ的积累系数（ｐ＜０．０５）．     

模拟水生态系统及其在环境研究中的应用

随着70年代污染生态毒理学的发展,微宇宙作为评价化学品的环境影响的有力工具日益受到重视。由于从点源和非点源释放的化学物质可经直接或间接途径进入水生态系统,水生微宇宙在环境研究中的应用发展很快。早期的研究工作侧重于化学污染物在水环境的归宿。自70年代末以来,研究注意力逐渐集中于有毒物质在水生态系统内不同生物学组织水平上的生态学效应。本文分下列4个方面进行述评:(1)关于模拟生态系统的若干基本概念;(2)应用于环境研究的不同类型水生微宇宙;(3)尚有争议的若干问题;(4)水生微宇宙技术应用的新动向和展望。     

微宇宙模拟溢油条件下沉积物中蓝细菌多样性

【目的】在不同浓度原油胁迫下,研究沉积物中原油降解规律及蓝细菌的响应机制,探讨蓝细菌对原油的耐受程度,并揭示蓝细菌种属结构组成的演替规律,为预测和判断溢油污染是否会造成富营养化等次生环境问题提供依据。【方法】建立微宇宙模拟实验体系,设置未添加原油对照组(CK组)及一系列高浓度原油处理组(25、125和250 g/kg干重,分别为LO组、MO组和HO组),通过气相色谱-氢火焰离子化检测器分析微宇宙培养期间原油降解规律。采用蓝细菌16SrRNA基因分析蓝细菌多样性和丰度变化规律,以及蓝细菌各种属的演替情况。【结果】微宇宙培养第31天时,在最低浓度处理组(LO组)沉积物表层出现片状绿色菌苔,而其他处理组和对照组未出现此现象。蓝细菌16SrRNA基因克隆文库结果表明,在溢油条件下所有处理组的蓝细菌多样性均降低,但有一些种属出现富集,如Oscillatoria和Prochlorococcus等。此外,也监测到大量的不可培养种属,预示着沉积物中可能存在新种属的蓝细菌。【结论】蓝细菌对原油具有较高耐受性,25 g/kg浓度原油会对蓝细菌生长产生刺激作用,且可能进一步引起蓝细菌富集。原油会引起蓝细菌多样性降低,但个别种属会发生富集,说明这些种属对原油具有较高耐受性,甚至发挥重要功能,如Oscillatoria具有固氮功能。本研究在分子水平上研究了蓝细菌对原油的响应,对蓝细菌分子生态研究具有重要意义。     

多氯联苯在模拟水生态系统中的分布、积累与迁移动态研究

利用微宇宙模拟水生态系统对多氯联苯在水体环境中的行为 ,包括多氯联苯在水体、沉积物、生物体 (皇冠草、河蚬、鲢 )不同分配相及生物体不同组织、器官中含量、分布以及迁移、富集等时间变化动态过程进行了研究。结果表明 ,水草对PCB有一定程度的吸收 ;河蚬对PCBs有明显的吸收积累 ,并且吸收达到平衡的时间较长。鱼体对PCB的吸收积累在不同组织中有明显的差别 ,在内脏和肌肉组织中积累较高 ,鳃组织中积累较低。     

沉水植物化感作用对西湖湿地浮游植物群落的影响

通过微宇宙实验,在控制光照和营养盐浓度的条件下分别研究了苦草(Vallisneria spiralis)、金鱼藻(Ceratophyllum demersum)和穗花狐尾藻(Myriophyllum spicatum)的化感作用对采集于杭州西湖湖西湿地的藻类密度、叶绿素a浓度、群落结构、多样性指数等的影响。其结果表明,3种沉水植物对微宇宙系统中的藻类都具有明显影响,藻类密度与叶绿素a浓度受到显著抑制,3个草-藻研究系统中藻类群落结构都发生了变化。在实验末期苦草组、金鱼藻组和穗花狐尾藻组中藻类总生物量(以细胞密度计)分别较初始值降低了37.06%、78.37%和83.40%。栅藻对3种沉水植物的化感作用敏感性较弱。藻类生物多样性方面,穗花狐尾藻系统中最高,其次是金鱼藻组,最后是苦草组,其Shannon-Wiener指数(H)分别为2.76、2.06和0.72,穗花狐尾藻组中H的显著高于苦草组(P0.05)。     

环境选择和扩散限制驱动温带森林土壤细菌群落的构建

环境选择和扩散限制是生态系统中生物群落构建的两个基本过程,而两者相对作用的大小因研究尺度、群落属性和类型等有所不同.目前对温带亚高山森林土壤微生物群落构建的驱动因子和机制尚缺乏了解.本文利用PCR-DGGE技术研究庞泉沟自然保护区内5种典型森林包括华北落叶松林、青杄林、白杄林、油松林以及桦树林的6个森林土壤细菌群落(Lp MC1、Lp MC2、Pw MC、Pm MC、Pt MC、BMC)的结构特征及其影响因素,分析细菌群落结构与环境因子的相关性,以及土壤因子、植被和空间因素对细菌群落结构的影响.结果表明:研究区各样地土壤细菌群落的结构和生物多样性具有显著差异,低海拔落叶松和油松土壤细菌群落多样性较高(20条带),白杄林土壤细菌群落(13条带)多样性最低,高海拔落叶松土壤细菌群落多样性最高;土壤环境因子,如pH、土壤含水量、总碳、总氮、土壤有机质、速效磷以及土壤酶活性与土壤细菌群落多样性和结构显著相关;样地土壤细菌群落的beta多样性与群落的空间距离呈显著相关,表明扩散限制对群落结构具有一定的影响;方差分解分析结果显示,6个样地细菌群落结构的驱动因素大小依次为土壤因子(0.27)、空间因素(0.19)和植被(0.15);将区域土壤微生物作为"源群落",微宇宙试验结果显示,土壤因子是细菌群落结构形成的主要驱动力(0.35),同时源群落丰富的物种多样性对微宇宙土壤细菌群落结构具有显著影响.总之,在局域尺度下,环境选择对温带森林土壤细菌群落结构动态和多样性发挥主导作用,地理距离对群落结构具有显著影响,即确定性过程和随机过程共同决定局域森林土壤细菌群落结构,前者占主导地位.对于土壤细菌群落而言,扩散群落的组成和结构受到源群落的多样性特征和环境因子的双重影响.     

石油污染生态系统中细菌群落结构及其代谢机制研究进展

石油化工产品的不合理处置与泄漏导致石油及其衍生物大量释放到环境中,由此造成的环境污染问题日益严重,石油污染已成为全球性公害之一。微生物修复技术凭借其成本低、环境友好等优势,广泛应用于石油污染的治理。大量研究表明功能微生物群落在石油污染生态系统的修复体系中发挥了重要的作用。其中,细菌是最主要、最活跃的石油降解微生物。然而,在原位/异位生物修复过程中,存在功能菌群在污染体系中难维持、易失调及石油烃降解途径不明晰等问题。因此,本文总结了石油污染自然生态系统和微宇宙实验体系中的细菌群落结构、石油烃代谢机制及相关功能基因,并对微生物法处理石油污染的未来研究方向提出展望,为石油污染场地生物修复方案的制定提供理论参考。     

水生态系统中宇宙发展现状

水生态系统中宇宙指人工构建的河流、湖泊、湿地、海洋等水生态系统近自然模拟装置,可以控制一定的物理、化学要素和生境条件,开展生物群落响应研究。中宇宙实验可以弥补传统实验室小型装置模拟要素过于简单,而野外现实系统复杂不可控制和难以开展对比实验的局限。本文列举了当前国际上多个科研机构长期运行的水生态系统中宇宙,将其归纳为流水型中宇宙、围隔装置、陆基模拟池、移动式水槽4类,各类中宇宙一般包括物理-生物模拟系统、自动调控系统、监测分析系统、中央控制系统。近年来,我国水生态系统的研究逐渐从单一环境要素向生态系统整体转变,对中宇宙模拟实验的需求愈加迫切。建议我国水生态系统中宇宙建设应提高结构复杂性,并与野外现场监测相结合,共同支撑更大尺度系统的整体模拟。     

Parasitic infection reduces dispersal of ciliate host

Parasitic infection can modify host mobility and consequently their dispersal capacity. We experimentally investigated this idea using the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata. We compared the short-distance dispersal of infected and uninfected populations in interconnected microcosms. Infection reduced the proportion of hosts dispersing, with levels differing among host clones. Host populations with higher densities showed lower dispersal, possibly owing to social aggregation behaviour. Parasite isolates that depleted host populations most had the lowest impact on host dispersal. Parasite-induced modification of dispersal may have consequences for the spatial distribution of disease, host and parasite genetic population structure, and coevolution.     

Effect of a mouthrinse containing Malva sylvestris on the viability and activity of microcosm biofilm and on enamel demineralization compared to known antimicrobials mouthrinses

The purpose of this study was to evaluate the antimicrobial (anti-biofilm) and anti-caries (enamel demineralization prevention) effects of Malva sylvestris (Malvatricin^® Plus) compared with known antimicrobial mouthrinses. Microcosm biofilm was produced on enamel, using inoculum from pooled human saliva mixed with McBain saliva (0.2% sucrose) for 14 days. The biofilm was treated with mouthrinses for 1 min day^?1. Oral-B^® Complete, Listerine^® Zero and Malvatricin^® Plus had the greatest effect on the reduction of biofilm viability (p < 0.0001). On the other hand, lactic acid production was reduced significantly with PerioGard^®, Noplak^® Max and Listerine^® Zero compared with the control (p < 0.0001). No significant differences were found among the mouthrinses with respect to the colony-forming unit counting (total microorganisms, total streptococci, mutans streptococci and lactobacilli) and extracellular polysaccharide production. Enamel demineralization was reduced significantly with PerioGard^®, Noplak^® Max and Malvatricin^® Plus compared with the control (p < 0.0001). Malva sylvestris has a comparable anti-caries effect to chlorhexidine mouthrinses.     

Degradation of Aroclor 1221 and survival of strains in soil microcosms

Three bacterial strains able to use different aromatic compounds as the sole carbon and energy source were tested for their potential to degrade Aroclor 1221 in soil microcosms when present in mixed culture. Disappearance of polychlorinated biphenyls (PCBs), occurrence of metabolites, release of chloride, and survival of the laboratory-selected strains were investigated under different conditions. In principle, complete mineralization of various congeners of Aroclor 1221, a technical mixture of PCBs, by the mixed culture was possible. The autochthonous microflora negatively affected the degradation due to formation of a toxic compound from 4-chlorobenzoate. 4-Chlorobenzoate was produced by one of the added strains, Pseudomonas sp. JHK, during degradation of 4-chlorobiphenyl. The unknown metabolite of 4-chlorobenzoate led to a rapid decrease in viable counts of the laboratory-selected strains in the soil microcosm.Correspondence to: J. Havel     

Climate change and Cognettia sphagnetorum: effects on carbon dynamics in organic soils

1. A microcosm experiment was performed to test the impacts of Cognettia sphagnetorum on carbon leaching in a cambic stagnohumic gley soil.
2. Leaching of dissolved organic carbon (DOC) was significantly enhanced by C.sphagnetorum, with the greatest effect being found in the upper, 0–6 cm, soil layers. The ratio of DOC to dissolved organic nitrogen (DON) in the leachate decreased in faunated systems, indicating that the enchytraeids were mobilizing carbon from organic matter with a low C to N ratio.
3. The vertical distribution of the enchytraeids had an effect on the production of DOC, and this vertical distribution is affected strongly by climate. It is proposed that increases in DOC found in a field soil-warming experiment with the same soil are largely a result of changes in the vertical distribution of these organisms.     

Surfactant enhances biodegradation of hydrocarbons: Microcosm and field study

The purpose of the present study was to provide new methods that would increase the rates of biodegradation of petroleum hydrocarbons in soil, thus reducing the time required to achieve a satisfactory level of residual hydrocarbon in an ex situ bioremediation. Results of laboratory studies on several techniques were used to guide our implementation of these methods in controlled field studies. Soils contaminated with nonvolatile hydrocarbons were treated with various combinations of (1) an anionic surfactant guanidinium cocoate (CGS), (2) a consortium of hydrocarbon‐degrading microorganisms, (3) a slow‐release form of nitrogen:urea, and (4) the bulking agent vermiculite. Laboratory results describing the activity of CGS have been presented previously (Jain et al., 1992). The amount and rate of hydrocarbon loss in treated soil was compared with hydrocarbon lost in soil that received no amendment other than water (water only). We also used a sheen screen method (Nelson et al., 1995), to assess the effectiveness of our field application of microorganisms.     

Chemotaxis increases vertical migration and apparent transverse dispersion of bacteria in a bench-scale microcosm

The success of in situ bioremediation is often limited by the inability to bring bacteria in contact with the pollutant, which they will degrade. A bench-scale model aquifer was used to evaluate the impact of chemotaxis on the migration of bacteria toward the source of a chemical pollutant. The model was packed with sand and aqueous media was pumped across horizontally, simulating groundwater flow in a homogenous aquifer. A vertical gradient in chemoattractant was created by either a continuous injection of sodium benzoate or a pulse injection of sodium acetate. A pulse of chemotactic Pseudomonas putida F1 or a non-chemotactic mutant of the same species was injected below the attractant. The eluent was sampled at the microcosm outlet to generate vertical concentration profiles of the bacteria and chemoattractant. Moment analysis was used to determine the center and variance of the bacterial profiles. The center of the chemotactic bacterial population was located at an average of 0.74 ± 0.07 cm closer to the level at which the chemoattractant was injected than its non-chemotactic mutant in benzoate experiments (P < 0.015) and 0.4 ± 0.2 cm closer in acetate experiments (P < 0.05). The transverse dispersivity of the chemotactic bacteria was 4 ± 1 × 10(-3) cm higher in benzoate experiments than the transverse dispersivity of the non-chemotactic mutant and 1 ± 2 × 10(-3) cm higher in acetate experiments. These results underscore the contribution of chemotaxis to improve transport of bacteria to contaminant sources, potentially enhancing the effectiveness of in situ bioremediation.     

Analysis of coastal lagoon metabolism as a basis for management

This work was carried out in a shallow eutrophic coastal lagoon (St. André lagoon, SW Portugal) which is artificially opened to the sea each year in early spring. Macrophytes, mainly Ruppia cirrhosa, are keystone species in this ecosystem covering up to 60% of its total area with peak biomasses over 500 g DW m^–2. The main objectives were to study ecosystem metabolism, to evaluate the metabolic contribution to the community of the macrophyte stands and their influence in the development of thermal stratification and bottom oxygen depletion.The work combined an experimental and a modelling methodology. The experimental approach included open water, mesocosm and microcosm seasonal experiments. During these experiments several physical, chemical and biological parameters were monitored in the lagoon and in plastic enclosures (mesocosms) for periods of 24 hours. The microcosm experiments followed the light-dark bottle technique. The simultaneous use of these different methodologies allowed the analysis of the contribution of the planktonic and benthic compartments to the ecosystem's oxygen budget.The modelling work was based on the mathematical simulation of heat and gas exchanges in a vertically resolved water column, under different macrophyte densities. Several simulations were carried out, in order to investigate the importance of the macrophytes in the development of water column stratification and anoxia.The simulation results suggest that macrophytes may greatly influence thermocline and oxycline development. This influence is proportional to their biomass and canopy height. It is suggested that controlled macrophyte biomass removal of up to 25% of available biomass in summer, may be useful in preventing bottom anoxia without compromising benthic net primary production.     

A microcosm investigation of fe (iron) removal using macrophytes of ramsar lake: A phytoremediation approach

The present study deals with the microcosm study of Fe (Iron) phytoremediation using Eichhornia crassipes, Lemna minor, Pistia stratiotes and Salvinia cucullata species collected from the Loktak Lake, a Ramsar Site which exists in north-eastern India (an Indo-Burma hotspot region). Efficiency of these four macrophytes was compared using different Fe concentrations of 1 mg L^?1, 3 mg L^?1 and 5 mg L^?1 for 4 days, 8 days and 12 days, respectively. E. crassipes was the most efficient macrophyte whereas L. minor was the least efficient. E. crassipes removed the highest percentage of Fe, i.e. 89% from 1 mg L^?1, 81.3% from 3 mg L^?1 and 73.2% from 5 mg L^?1 in 12-day experiment.     

Effect of soil moisture on bioremediation of chlorophenol-contaminated soil

A chlorophenol-contaminated soil was tested for the biodegradability in a semi-pilot scale microcosm using indigenous microorganisms. More than 90% of 4-chlorophenol and 2,4,6-trichlorophenol, initially at 30 mg kg^–1, were removed within 60 days and 30 mg pentachlorophenol kg^–1 was completely degraded within 140 days. The chlorophenols were degraded more effectively under aerobic condition than under anaerobic condition. Soil moisture had a significant effect with the slowest degradation rate of chlorophenols at 25% in the range of 10–40% moisture content. At 25–40%, the rate of chlorophenol degradation was directly related to the soil moisture content, whereas at 10–25%, it was inversely related. Limited oxygen availability through soil agglomeration at 25% moisture content might decrease the degradation rate of chlorophenols.     

The scientific basis of bioassays

The ultimate goal of ecotoxicological testing is to predict ecological effects of chemicals and other stressors. Since damage should be avoided rather than corrected after it occurs, the predictive value of such tests is crucial. A modest base of evidence shows that, in some cases, extrapolations from bioassays on one species to another species are reasonably accurate and, in other cases, misleading. Extrapolations from laboratory bioassays to response in natural systems at the population level are effective if the environmental realism of the bioassay is sufficiently high. When laboratory systems are poor simulations of natural systems, gross extrapolation errors may result. The problem of extrapolating among levels of biological organization has not been given the serious attention it deserves, and currently used methodologies have been chosen for reasons other than scientific validity. As the level of biological organization increases, new properties are added (e.g., nutrient cycling, energy transfer) that are not readily apparent at the lower levels. The measured responses (or end points) will not be the same at all levels of biological organization, making the validation of predictions difficult. Evidence indicates that responses of ecologically complex laboratory systems correspond to predicted and documented patterns in stressed ecosystems. The difficulties of improving the ecological evidence used to predict adverse effects are not insurmountable since the essence of predictive capability is the determination of effects thresholds at all levels of organization. The dilemma between basing predictive schemes on either traditional or holistic methods can only be solved by facing scientific and ethical questions regarding the adequacy of evidence used to make decisions of environmental protection.