Polaromonas and Hydrogenophaga species are the predominant bacteria cultured from granular activated carbon filters in water treatment

Aim:  Identification of the predominating cultivable bacteria in granular activated carbon (GAC) filters used in a variety of water treatment plants for selecting representative strains to study the role of bacteria in the removal of dissolved organic matter.
Methods and Results:  Bacterial isolates were collected from 21 GAC filters in nine water treatment plants treating either ground water or surface water with or without oxidative pretreatment. Enrichment of samples in dilute liquid medium improved culturability of the bacteria by approximately log unit, to 9% up to 70% of the total cell counts. Genomic fingerprinting and 16S rDNA sequence analysis revealed that most (68%) of the isolates belonged to the Betaproteobacteria and 25% were identified as Alphaproteobacteria . The number of different genera within the Betaproteobacteria was higher in the GAC filters treating ozonated water than in the filters treating nonozonated water. Polaromonas was observed in nearly all of the GAC filters (86%), and the genera Hydrogenophaga , Sphingomonas and Afipia were observed in 43%, 33% and 29% of the filter beds, respectively. AFLP analysis revealed that the predominating genus Polaromonas included a total of 23 different genotypes.
Conclusions:  This study is the first to demonstrate that Polaromonas , which has mainly been observed in ultraoligotrophic freshwater environments, is a common component of the microbial community in GAC filters used in water treatment.
Significance and Impact of the Study:  The predominance of ultraoligotrophic bacteria in the GAC filters indicates that very low concentrations of substrates are available for microbial growth. Polaromonas species are suited for further studies on the nutritional versatility and growth kinetics enabling the modelling of biodegradation processes in GAC filters.     

Basic examinations on chemical pre-oxidation by ozone for enhancing bioremediation of phenanthrene contaminated soils

Biological treatment of polycyclic aromatic hydrocarbons (PAH) has been demonstrated to be a feasible and common remediation technology which has been successfully applied to the clean-up of contaminated soils. Because bioavailability of the contaminants is of great importance for a successful bioremediation, a chemical pre-oxidation step by ozone was tested to enhance the subsequent biodegradation steps. Oxidation of PAH by ozone should result in reaction products that have a better solubility in water and thus a better bioavailability. A major part of this work was done by examinations of the model substance phenanthrene as a typical compound of PAH. After initial ozonation of phenanthrene, analysis by GC-MS showed at least seven identified conversion-products of phenanthrene. In comparison with phenanthrene these conversion products were more efficiently biodegraded by Sphingomonas yanoikuyae or mixed cultures when the ozonation process resulted in monoaromatic compounds. Primary ozonation products with biphenylic structures were found not to be biodegradable. Investigations into the toxicity of contaminated and ozonated soils were carried out by well-established toxicity assays using Bacillus subtilis and garden cress. The ozonated soils surprisingly showed higher toxic or inhibitory effects towards different organisms than the phenanthrene or PAH itself. The microbial degradation of phenanthrene in slurry reactors by S. yanoikuyae was not enhanced significantly by preozonation of the contaminated soil.     

Efficacy of ozone in eradication of Legionella pneumophila from hospital plumbing fixtures.

The effect of ozonation of supply water for one wing of an unoccupied hospital building which had positive cultures for Legionella pneumophila from multiple potable water fixtures was studied in a prospective, controlled fashion. Mean ozone residual concentrations of 0.79 mg/liter eradicated L. pneumophila from the fixtures, but so did nonozonated water in the control wing fixtures. The efficacy of the nonozonated water was most probably due to a mechanical flushing effect and to an unexpected rise in the chlorine content of the supply water. Determination of the in vitro activity of ozone against L. pneumophila did not predict the efficacy of its eradication from water fixtures treated with ozone.     

Estimation of biological kinetic parameters from an analysis of the BOD curve of waste waters–effects of a chemical preoxidation

Urban waste waters were treated with pure ozone or combinations of ozone, hydrogen peroxide and/or UV radiation to study the course of resulting BOD (biological oxygen demand)-time profiles and to propose a kinetic model. BOD-time profiles of chemically treated waste waters show an initial lag period that first order kinetic models cannot describe. A second order kinetic model is then proposed that satisfactorily fits experimental BOD-time profiles, except when hydrogen peroxide has been used. In these cases, BOD-time profiles present the highest lag periods observed. By applying this model, three parameters are determined: the biokinetic constant (k) which is an index of the biological removal rate; the potential amount of biodegradable matter (BOD_T), and the measure of the size of inocula and microbial activities of microoganisms (λ). The model was checked with experimental results of BOD-time profiles corresponding to both untreated and chemically ozonated urban waste waters. Ozonated waste waters showed the highest values of k and BOD_T, which implies an improvement of waste water biodegradability after ozonation. However, values of λ corresponding to ozonated waste waters presented lower values than those of untreated waste waters. This was due to the lag period observed in the BOD-time profile, which was a consequence of a lack of microorganism acclimation to ozonated waste waters. The effect of the ozone does, pH and carbonates during ozonation on COD (chemical oxygen demand) and the above indicated parameters was also studied. There was an optimum ozone dose which was 138 mg/l for this specific system. This led to the highest biodegradable fraction (φ) and the highest biokinetic constant (39% increase in φ and 4.7- fold increase in the value of k, respectively, compared to untreated waste waters.). Another significant fact was that a higher COD reduction was observed in the absence of carbonate during ozonation at basic pH values. In addition, the percentage of variation in the biodegradable fraction (Δφ) of ozonated waste water increased compared to the untreated waste water at acid pH. The results suggest that ozonolysis, the direct molecular ozone way of reaction, due to its selective character, increases the biodegradability of waste water more than other chemically advanced oxidation processes based on hydroxyl radical reactions.     

The vertical distribution of below-ground biomass in grassland communities in relation to grazing regime and habitat characteristics

Abstract. 40 sites, representing different pasture types in Northwest Spain, were sampled in respect of their floristic composition, distribution of above and below-ground biomass and environmental and physical variables. Five plant community types were identified by classification techniques of plant species composition. These communities were then characterized in terms of the percentage of ground covered by herbaceous and shrub vegetation, stones, rocks and gaps as well as their topographic location and characteristics of the shallow soil (pH, organic matter, nitrogen and calcium content). Bio-mass was assessed in terms of above-ground structures, surface crowns and three below-ground layers to a depth of 10 cm. Three types of grazing regime were distinguished: Concentrated Intense Grazing in early spring (CIG), Extended Intense Grazing throughout the spring (EIG), and Non-Intense Grazing (NIG). Grazing regime showed the highest association with plant community type and three broad categories were identified: xeric stressed pastures, which nevertheless received CIG, mesic pastures with EIG, and three kinds of NIG mesic pastures. The xeric communities had the highest proportion of aboveground biomass, as a consequence of their greater proportion of woody perennials. These xeric communities displayed a more gradual reduction in below-ground biomass with depth than mesic pastures, a likely consequence of the low water content in the upper soil layers. The mesic communities had a high concentration of below-ground biomass in the upper layers when they were intensely grazed. However, when grazing was low (i.e. NIG situations), these communities had greater variability in biomass profiles than any of the other pasture types. Possible causes of the patterns in biomass distribution of the intensely grazed pastures are discussed.     

Effects of omnivorous filter‐feeding fish and nutrient enrichment on the plankton community and water transparency of a tropical reservoir

1. The major aim of this study was to test the hypothesis that nutrient enrichment and the introduction of the Nile tilapia (Oreochromis niloticus), an exotic omnivorous filter‐feeding fish, operate interdependently to regulate plankton communities and water transparency of a tropical reservoir in the semi‐arid northeastern Brazil. 2. A field experiment was performed for 5 weeks in 20 enclosures (9.8 m³) to which four treatments were randomly allocated: tilapia addition (F), nutrient addition (N), tilapia and nutrient addition (F + N) and a control treatment with no tilapia or nutrient addition (C). A two‐way repeated measures anova was undertaken to test for time, tilapia and nutrient effects and their interactions on water transparency, total phosphorus and total nitrogen concentrations, phytoplankton biovolume and zooplankton biomass. 3. Nutrient addition had no effect except on rotifer biomass, but there were significant fish effects on the biomass of total zooplankton, copepod nauplii, rotifers, cladocerans and calanoid copepods and on the biovolume of total phytoplankton, large algae (GALD ≥ 50 μm), Bacillariophyta and Zygnemaphyceae and on Secchi depth. In addition, we found significant interaction effects between tilapia and nutrients on Secchi depth and rotifers. Overall, tilapia decreased the biomass of most zooplankton taxa and large algae (diatoms) and decreased water transparency, while nutrient enrichment increased the biomass of rotifers, but only in the absence of tilapia. 4. In conclusion, the influence of fish on the reservoir plankton community and water transparency was significant and even greater than that of nutrient loading. This suggests that biomanipulation of filter‐feeding tilapias may be of importance for water quality management of eutrophic reservoirs in tropical semi‐arid regions.     

Systematic analysis of biochemical performance and the microbial community of an activated sludge process using ozone-treated sludge for sludge reduction

Two lab-scale bioreactors (reactors 1 and 2) were employed to examine the changes in biological performance and the microbial community of an activated sludge process fed with ozonated sludge for sludge reduction. During the 122 d operation, the microbial activities and community in the two reactors were evaluated. The results indicated that, when compared with the conventional reactor (reactor 1), the reactor that was fed with the ozonated sludge (reactor 2) showed good removal of COD, TN and cell debris, without formation of any excess sludge. In addition, the protease activity and intracellular ATP concentration of reactor 2 were increased when compared to reactor 1, indicating that reactor 2 had a better ability to digest proteins and cell debris. DGGE analysis revealed that the bacterial communities in the two reactors were different, and that the dissimilarity of the bacterial population was nearly 40%. Reactor 2 also contained more protozoa and metazoa, which could graze on the ozone-treated sludge debris directly.     

Soil and vegetation responses to hydrological manipulation in a partially drained polje fen in New Zealand

Anthropogenic drainage causes loss of natural character in herbaceous wetlands due to increased soil oxygen penetration. We related vegetation gradients in a New Zealand polje fen to long-term effects of drains by using hydrological, edaphic and vegetation data, and a before-after-control-impact (BACI) design to test responses to experimental drain closure. Soil profiles and continuous water level records revealed a site subject to frequent disturbance by intense but brief floods, followed by long drying periods during which areas close to drains experienced lower water tables and more variable water levels. Classification of vegetation data identified 12 groups along a moisture gradient, from dry areas dominated by pastoral alien species, to wet communities dominated by native wetland sedges. Lower total species diversity and native representation in pastoral communities were related to the high proportion of alien competitor and competitor-disturbance species, compared with the stress tolerator-dominated flora of other groups. Species–environment relationships revealed highly significant correlations with soil water content and aeration as measured by redox potential (E_H) and steel rod oxidation depth, as well as soil nutrient content and bulk density. Comparison of root anatomy confirmed greater development of flood-tolerant traits in native species than in pastoral aliens, and vegetation N:P ratios indicated that most communities were probably nitrogen-limited. Flooding rapidly re-established wetland hydrology in dried sites in the impact area, and lowered E_H and soil oxidation depth, but had no effect on N and P availability. Presence and cover of pastoral alien species decreased in these areas. This study supports the use of hydrological manipulation as a tool for reducing soil oxidation and thus the impact of alien plant species at restoration sites with minimal intervention, but suggests the need for detailed information on species flooding tolerances and hydrological preferences to underpin this approach.     

How does the vertical distribution of chlorophyll vary in littoral sediments of small lakes?

1. In this study, sediment chlorophyll profiles at twenty littoral stations in three oligo‐mesotrophic lakes were compared to test whether the vertical distribution of chlorophyll is related to site characteristics (light availability, temperature, physical disturbances) and whether these profiles differ between shallow and deep portions of the littoral zone.
2. The magnitude of chlorophyll peaks at the sediment surface did not vary with light intensity. Chlorophyll peaks in the shallow littoral zone had a weak tendency to decrease with increasing effective fetch. The magnitude of chlorophyll peaks at deeper sites was more closely related to water temperature than to substrate slope.
3. High chlorophyll concentrations were measured down to 1–3 cm in the sediments, both at shallow (< 2.5 m) and deep (4–10 m) stations. The depth to which high chlorophyll was found in sediments did not vary with effective fetch or sediment water content, two indices of wave disturbance in the shallow littoral zone, or with substrate slope, an index of sediment stability in the deep littoral zone. Sediment mixing is apparently not related to common indices of physical disturbances.
4. Between 8 and 100% of sediment surface chlorophyll was 'retained' 4–5 cm into the sediments. The proportion of chlorophyll 'retained' in littoral sediments increased with increasing depth, increasing lake productivity (total phosphorus concentration) and increasing lake pH.
5. Among‐core variability (standard error/mean) in chlorophyll concentration at the sediment surface ranged from less than 1% to 33% at different stations and was highest at shallow, exposed sites. These levels of variability are similar to those found in other periphytic communities.     

Functional and Structural Responses of a Degradative Microbial Community to Substrates with Varying Degrees of Complexity in Chemical Structure

Abstract The objective of the present study was to determine whether cultivation of a degradative community on substrates with varying degrees of chlorination and complexity in chemical structure, as well as cultivation in batch and flow cell culture, would alter the community's functional capability. The community was isolated from oil-contaminated soil and maintained in the laboratory on 2,4,6-trichlorobenzoic acid for 5 months before its ability to grow on 15 different chemicals as sole carbon source was evaluated in batch and flow cell systems. While the community could grow and develop biofilms in flow cells on all the substrates, only 11 of the 15 substrates could support growth in batch culture. Although biofilm development was less extensive on chemicals such as pentachlorophenol (2.09% average area covered by biofilm; average biofilm depth = 3 μm) than on 2,4,6-trichlorobenzoic acid (50.84% area covered; biofilm depth = 6.4 μm), no correlation was observed between the degree of chlorination, or number of rings, and the number of planktonic cells or biofilm biomass. In contrast, physicochemical characteristics such as the octanol/water partition coefficient had a significant effect on the development of biofilm biomass. In the case of planktonic communities, the degree of chlorination and ring number also had no effect on the BIOLOG carbon utilization profiles of the resulting communities. Although the sessile communities generally clustered separately from their planktonic counterparts, principal component analysis of carbon utilization profiles of the sessile communities showed different grouping between growth on chlorinated and nonchlorinated substrates. Analysis of the degradative community maintained on 2,4,6-trichlorobenzoic acid over an extended period further showed that adaptation to a new chemical environment is a rather slow process, since the substrate utilization profiles did not stabilize even after 12 months. These results demonstrate the flexibility in metabolic ability and community structure found in microbial communities. Received: 30 November 1998; Accepted: 19 May 1999     

Efficacy of ozonated water against various food-related microorganisms.

The antimicrobial effects of ozonated water in a recirculating concurrent reactor were evaluated against four gram-positive and four gram-negative bacteria, two yeasts, and spores of Aspergillus niger. More than 5 log units each of Salmonella typhimurium and Escherichia coli cells were killed instantaneously in ozonated water with or without addition of 20 ppm of soluble starch (SS). In ozonated water, death rates among the gram-negative bacteria--S. typhimurium, E. coli, Pseudomonas aeruginosa, and Yersinia enterocolitica--were not significantly different (P > 0.05). Among gram-positive bacteria, Listeria monocytogenes was significantly P < 0.05) more sensitive than either Staphylococcus aureus or Enterococcus faecalis. In the presence of organic material, death rates of S. aureus compared with L. monocytogenes and E. coli compared with S. typhimurium in ozonated water were not significantly (P > 0.05) affected by SS addition but were significantly reduced (P < 0.05) by addition of 20 ppm of bovine serum albumin (BSA). More than 4.5 log units each of Candida albicans and Zygosaccharomyces bailii cells were killed instantaneously in ozonated water, whereas less than 1 log unit of Aspergillus niger spores was killed after a 5-min exposure. The average ozone output levels in the deionized water (0.188 mg/ml) or water with SS (0.198 mg/ml) did not differ significantly (P < 0.05) but were significantly lower in water containing BSA (0.149 mg/ml).     

Recruitment of Antarctic marine eukaryotes onto artificial surfaces

Activities related to Antarctic research stations have caused significant local impacts on the marine environment, potentially affecting the recruitment of benthic invertebrates. Herein, we report the community structure of recruiting marine eukaryotes onto artificial substrata using molecular techniques. Slides were deployed at three sites adjacent to McMurdo Station, Scott Base, and Cape Armitage in McMurdo Sound. Denaturing gradient gel electrophoresis (DGGE) analysis revealed complex and diverse eukaryotic communities had established on artificial surfaces deployed at a range of site and depth regimes after 12 months. Analysis of similarity results detected significantly greater variability in community profiles among sites than within sites. The nonmetric multidimensional scaling plot constructed from DGGE banding patterns revealed different benthic communities had established at 12 and 18 m depths. Despite this, the variation in community composition was greater among sites than between depths, especially at Cape Armitage and Scott Base. Sequence analysis of excised DGGE bands revealed a predominance of arthropod and dinoflagellate sequences at Cape Armitage. In contrast, a wide diversity of phyla including cnidaria, bryozoa, protozoa, dinoflagellates, arthropods, platyhelminths, and annelids were present adjacent to the two research stations. The abundance of diatoms detected in Cape Armitage benthic assemblages exceeded the abundance of diatoms from McMurdo Station and Scott Base by almost two orders of magnitude. The discovery that distinct eukaryotic communities recruit at different sites and depths is probably due to complex interactions between multiple factors including water quality, larval supply, and light. The detection of sessile phyla on slides at each of the sites indicates that the pollution profiles present at each site is not an impediment to successful recruitment of these species.     

Contrasting taxonomic stratification of microbial communities in two hypersaline meromictic lakes

Hypersaline meromictic lakes are extreme environments in which water stratification is associated with powerful physicochemical gradients and high salt concentrations. Furthermore, their physical stability coupled with vertical water column partitioning makes them important research model systems in microbial niche differentiation and biogeochemical cycling. Here, we compare the prokaryotic assemblages from Ursu and Fara Fund hypersaline meromictic lakes (Transylvanian Basin, Romania) in relation to their limnological factors and infer their role in elemental cycling by matching taxa to known taxon-specific biogeochemical functions. To assess the composition and structure of prokaryotic communities and the environmental factors that structure them, deep-coverage small subunit (SSU) ribosomal RNA (rDNA) amplicon sequencing, community domain-specific quantitative PCR and physicochemical analyses were performed on samples collected along depth profiles. The analyses showed that the lakes harbored multiple and diverse prokaryotic communities whose distribution mirrored the water stratification patterns. Ursu Lake was found to be dominated by Bacteria and to have a greater prokaryotic diversity than Fara Fund Lake that harbored an increased cell density and was populated mostly by Archaea within oxic strata. In spite of their contrasting diversity, the microbial populations indigenous to each lake pointed to similar physiological functions within carbon degradation and sulfate reduction. Furthermore, the taxonomy results coupled with methane detection and its stable C isotope composition indicated the presence of a yet-undescribed methanogenic group in the lakes'' hypersaline monimolimnion. In addition, ultrasmall uncultivated archaeal lineages were detected in the chemocline of Fara Fund Lake, where the recently proposed Nanohaloarchaeota phylum was found to thrive.     

臭氧处理海水对扇贝卵的孵化及幼虫生长的影响

主要研究了用臭氧处理海水在经过连续充气曝气12、24h、不经充气曝气的处理水及没经臭氧处理的正常海水,进行海湾扇贝、虾夷扇贝受精卵的孵化和幼虫培育实验。结果表明,海湾扇贝受精卵在经过24h曝气的处理水中孵化率最高为92％,其次为没经过处理的正常海水为76％,曝气12h为16％,没经过曝气的为0;虾夷扇贝受精卵在经过24h曝气的处理水中孵化率最高为88%,其次为没经过处理的正常海水为85％,曝气12h为15％,没经过曝气为0。海湾扇贝幼虫培养在没经过处理的正常海水和经24h曝气的处理水中生长较快,曝气12h较慢;虾夷扇贝幼虫则是没经过处理的正常海水生长最快,其次是经24h曝气的处理水,而曝气12h较慢,成活率方面也表现出一定的差异,从而为臭氧处理海水在贝类育苗上的应用提供一定的指导。     

Microbial distribution and diversity in saturated, high pH, uranium mine tailings, Saskatchewan, Canada

Microbiological analyses were conducted on core samples collected along a vertical profile (0-66 m below surface) from the tailings management facility (TMF) at the Rabbit Lake uranium mine in northern Saskatchewan, Canada. Bacterial numbers in the core materials were similar to surrounding soils and surface waters, regardless of the seemingly unfavorable pH (mean=9.9) and temperature (approximately 0 degrees C) in the TMF. The greatest number of viable cells (105 CFU/g) was detected at the interface between the tailings and overlying standing water, below which cell counts decreased rapidly with depth. Whole-community metabolic profiles for samples from the different depths grouped into 3 clusters; however, these groups could not be positively correlated with sampling depth, temperature, redox potential, pH, or ore-mill feed. Flow-cell studies demonstrated microbial communities in the tailings surface water could develop biofilms and maintain cell activity at both pH 10 and 7, and altering the pH between these 2 values had little effect on biofilm viability. These results demonstrate the resilience and adaptive nature of naturally occurring microbial communities and signify a potential role of microbial activity in the long-term geochemical evolution of the TMF.     

Environmental significance of the potential for mer(Tn21)-mediated reduction of Hg2+ to Hg0 in natural waters.

The role of mer(Tn21) in the adaptation of aquatic microbial communities to Hg2+ was investigated. Elemental mercury was the sole product of Hg2+ volatilization by freshwater and saline water microbial communities. Bacterial activity was responsible for biotransformation because most microeucaryotes did not survive the exposure conditions, and removal of larger microbes (greater than 1 micromole) from adapted communities did not significantly (P greater than 0.01) reduce Hg2+ volatilization rates. DNA sequences homologous to mer(Tn21) were found in 50% of Hg2+-resistant bacterial strains representing two freshwater communities, but in only 12% of strains representing two saline communities (the difference was highly significant; P less than 0.001). Thus, mer(Tn21) played a significant role in Hg2+ resistance among strains isolated from fresh waters, in which microbial activity had a limited role in Hg2+ volatilization. In saline water environments in which microbially mediated volatilization was the major mechanism of Hg2+ loss, other bacterial genes coded for this biotransformation.     

稳定溶解臭氧水对皮肤创面炎症的治疗效果

目的:探讨浓度为1.8-3.2 mg/L溶解臭氧水冲洗控制皮肤创口炎症引发的红肿痛的临床效果。方法:将40例接受激光皮肤除斑治疗的患者分为两组,其中实验组20例患者采用浓度为1.8-3.2 mg/L溶解臭氧水冲洗皮肤创面,而对照组20例患者采用冰袋冷敷的方式处理创面。观察并比较两组患者皮肤创面红肿的改善情况以及两种治疗方法的临床效果。结果:1疼痛症状改善情况:实验组显效20例,对照组显效0例,实验组患者显效率明显高于对照组,差异具有统计学意义(P0.01)。2临床体征改善情况:实验组显效20例,对照组显效0例,实验组患者显效率明显高于对照组,差异具有统计学意义(P0.01)。结论:浓度1.8-3.2mg/L溶解臭氧水对于炎症引发的皮肤创面红肿症状具有显著的疗效,不仅能够抑制炎症发展,而且有利于促进创面愈合,值得在临床广泛推广应用。     

Environmental significance of the potential for mer(Tn21)-mediated reduction of Hg2+ to Hg0 in natural waters

The role of mer(Tn21) in the adaptation of aquatic microbial communities to Hg2+ was investigated. Elemental mercury was the sole product of Hg2+ volatilization by freshwater and saline water microbial communities. Bacterial activity was responsible for biotransformation because most microeucaryotes did not survive the exposure conditions, and removal of larger microbes (greater than 1 micromole) from adapted communities did not significantly (P greater than 0.01) reduce Hg2+ volatilization rates. DNA sequences homologous to mer(Tn21) were found in 50% of Hg2+-resistant bacterial strains representing two freshwater communities, but in only 12% of strains representing two saline communities (the difference was highly significant; P less than 0.001). Thus, mer(Tn21) played a significant role in Hg2+ resistance among strains isolated from fresh waters, in which microbial activity had a limited role in Hg2+ volatilization. In saline water environments in which microbially mediated volatilization was the major mechanism of Hg2+ loss, other bacterial genes coded for this biotransformation.     

Microbial communities in wetlands of the Athabasca oil sands: genetic and metabolic characterization

Naphthenic acids are a complex family of naturally occurring cyclic and acyclic carboxylic acids that are present in the acidic fraction of petroleum. Naphthenic acids are acutely toxic to aquatic organisms. Previous studies showed that wetland sediments exposed to oil sands process water containing naphthenic acids had higher rates of naphthenic acid degradation in vitro compared with unexposed wetlands. In this study we compare the microbial community structures in sediments from wetlands exposed to different amounts of oil sands process water using BIOLOG, phospholipid fatty acid analysis and denaturing gradient gel electrophoresis of total bacterial DNA. Community profiles were compared using cluster analysis. BIOLOG profiles were primarily influenced by seasonal trends rather than naphthenic acids content. In contrast, phospholipid fatty acid analysis comparisons clustered communities that had higher levels of residual oil, although this association was not strong. In contrast, cluster diagrams produced from the denaturing gradient gel electrophoresis data clearly separated bacterial communities according to naphthenic acids concentrations, indicating that naphthenic acids content was a major influence on the composition of the bacterial community. In addition, denaturing gradient gel electrophoresis profiles indicated that naphthenic acids-exposed bacterial communities were homogeneous on a scale of meters, whereas unexposed (off-site) wetlands were less homogeneous.     

冬季水鸟对崇明东滩水产养殖塘的利用

自然湿地的丧失和退化给依赖湿地生存的水鸟带来了严重威胁,人工湿地作为水鸟栖息地的功能日益受到关注.水产养殖塘是人工湿地的重要类型之一.通过研究崇明东滩水产养殖塘冬季水鸟群落组成及其栖息地特征,发现大面积养殖塘比小面积养殖塘吸引更多种类和更高密度的水鸟.养殖塘在放水前水位较高时吸引更多游禽栖息,而在放水后水位较低时吸引更多涉禽;在放水过程中,养殖塘中水鸟的种类最多,密度最大.另外,在放水的不同时期,不同的环境因子对水鸟群落的影响不同:放水之前,养殖塘水面面积和平均水深是水鸟种类和数量的主要影响因子,其中游禽种类和数量受水面面积影响较大,涉禽种类和数量受平均水深影响较大;放水过程中,裸地面积、芦苇面积、干扰程度、平均水深和水深变异对水鸟、游禽和涉禽的种类和数量起主要作用;放水之后,水深变异对水鸟种类和数量的影响较大,而影响游禽种类和数量的主要因子是水面面积,影响涉禽种类和数量的主要因子是水深变异.研究表明,通过对影响水鸟栖息地利用的主要因子的有效管理,养殖塘在提供经济效益的同时也能为水鸟提供适宜的栖息地.