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1.
In the last two centuries, native European oak forests have undergone a dramatic decline related to increasing human pressure for agriculture and urbanization. Oak forests were either completely eradicated and transformed into agricultural landscapes or replaced by second-growth formations. Intensive forest management and the replacement of native forests with production forests or arable lands are recognized amongst the main threats to many lichens in Europe. In this study, we used historical information on the epiphytic lichen biota which was hosted in a native oak-dominated forest of Northern Italy to identify shifts of lichen communities due to the changes in land use which occurred during the last two centuries. We also compared the epiphytic lichen communities inhabiting remnant oak forests with those found in the habitats that have replaced native forests: black-locust forests and agrarian landscapes. Almost all the species sampled during the 19th century are now extinct. The loss of native habitat and the subsequent invasion by black locust were probably the most influential factors which affected the composition of lichen communities, causing the local extinction of most of the species historically recorded. Despite the fact that oak remnants host only a few species which were historically recorded, and that they currently are the lichen poorest habitat in the study region, they host lichen assemblages differing from those of black-locust forests and agrarian stands. In these habitats lichen assemblages are mainly composed of species adapted to well-lit, dry conditions and tolerating air pollution and eutrophication. This pattern is likely to be common also in other lowland and hilly regions throughout Northern Italy where oak forests are targeted among the habitats of conservation concern at the European level. For this reason, a national strategy for biodiversity conservation and monitoring of lowlands forests should provide the framework for local restoration projects. 相似文献
2.
Spanish holm oak (Quercus ilex subsp. ballota) open woodlands (dehesas) maintain a high diversity of plants and animals compared to other forested Mediterranean habits, but little is known about the responses of epiphytic lichens to different management regimes that are applied to this woodland type. The present study was carried out in central-southern Spain and included four management regimes: agriculture, grazing of sheep, grassland grazed by wild ungulates (deer), and abandoned dehesas covered by shrubs. Total species richness and cover exhibited considerable variation among management regimes. Both parameters tended to decrease with the intensity of management, abandoned dehesas maintaining a higher number of species than more intensively managed habitats. Lichen composition also significantly differed among the four regimes. Nitrophytic species were clearly associated with more intensive management regimes (farming or livestock management), whereas non-nitrophytic species favored abandoned dehesas. 相似文献
3.
Simge Andolsun Charles H. CulpJeff Haberl Michael J. Witte 《Energy and Buildings》2011,43(7):1663-1675
For low-rise buildings, the heat losses or gains through the ground coupled building envelope can be a significant load component. Studies have shown that current simulation tools give dissimilar results for the ground coupled heat transfer (GCHT) with basements. This paper quantifies and explains the differences between EnergyPlus and DOE-2.1e (DOE-2) basement GCHTs based on their results for an all electric code house in a hot and humid climate zone. The code house was modeled with two basement configurations i.e. a conditioned basement and an unconditioned crawlspace. DOE-2 was used with Winkelmann's basement model and EnergyPlus was used with its GCHT calculator utility, Basement. The results revealed that the ground isolated EnergyPlus houses used 3-23% more cooling, 12-29% less heating and 3-7% lower overall HVAC electricity use when compared to the ground isolated DOE-2 houses. Ground coupling added up to three times more heat loss in EnergyPlus than in DOE-2. This increased the overall energy use difference between these two programs from 3-7% (ground isolated) to 14-25% (ground coupled). These results showed that a truth standard is required for basement heat transfer calculations of low-rise buildings. 相似文献
4.
The effects of thermal modification on crystalline structure of cellulose in soft and hardwood 总被引:1,自引:0,他引:1
In this study the crystallinity and estimations of relative triclinic (Iα) and monoclinic (Iβ) structure content of cellulose isolated from heated spruce (Picea orientalis) and beech (Fagus orientalis) wood samples were determined by using Fourier Transform Infrared (FT-IR) spectrometry. Heat treatment was applied on the test samples in an oven at three different temperatures (150, 180 and 200 °C) and two different durations (6 and 10 h) under atmospheric pressure. It was determined that crystallinity of cellulose in wood samples increased with thermal modification. The results indicate that the changes in crystallinity of cellulose in wood samples related to not only temperature but also time during thermal modification. Iα/Iβ ratio of cellulose in spruce and beech wood samples changed with thermal modification, but it was established that monoclinic structure was dominant in cellulose crystalline structure. It was designated that the crystalline structure of cellulose in spruce wood samples affected from thermal modification more than in beech wood samples. 相似文献
5.
Hepatic levels of metal and metallothioneins in two commercial fish species of the Northern Iberian shelf 总被引:2,自引:0,他引:2
Metal levels (Cd, Pb, Hg, Cr, Fe, Cu, Zn) together with metallothioneins (MTs) were determined in the liver of two commercial fish species collected along the Northern Iberian coast. The four-spotted megrim (Lepidorhumbos boscii) and the pouting (Trisopterus luscus) were selected as representative species of the middle/outer (200-500 m) and inner shelf (70-120 m), respectively. Metal pollution in the middle/outer shelf was mostly detected in the Asturias and Basque Country areas, whereas in the inner shelf, pollution was widely spread along the coast. Significantly high levels of Pb, Cd, Cr and Hg were detected in T. luscus from different sampling sites and associated to anthropogenic pressure. MTs were induced in fish that had higher amounts of Zn, Cd, Cr and Hg in their livers, supporting the use of MT as a biomarker of metal exposure. The study supports the usefulness of the selected fish species as sentinel organisms for future biomonitoring studies. 相似文献
6.
Removal of Giardia and Cryptosporidium in drinking water treatment: a pilot-scale study 总被引:9,自引:0,他引:9
Giardia and Cryptosporidium have emerged as waterborne pathogens of concern for public health. The aim of this study is to examine both parasites in the water samples taken from three pilot-scale plant processes located in southern Taiwan, to upgrade the current facilities. Three processes include: conventional process without prechlorination (Process 1), conventional process plus ozonation and pellet softening (Process 2), and integrated membrane process (MF plus NF) followed conventional process (Process 3). The detection methods of both parasites are modified from USEPA Methods 1622 and 1623. Results indicated that coagulation, sedimentation and filtration removed the most percentage of both protozoan parasites. The pre-ozonation step can destruct both parasites, especially for Giardia cysts. The microfiltration systems can intercept Giardia cysts and Cryptosporidium oocysts completely. A significant correlation between water turbidity and Cryptosporidium oocysts was found in this study. The similar results were also found between three kinds of particles (phi=3-5,5-8 and 8-10 microm) and Cryptosporidium oocysts. 相似文献
7.
Natália Rust Neves Alan Carlos Costa Eduardo Gusmão Pereira 《The Science of the total environment》2009,407(12):3740-3745
The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPMFe) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPMFe application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers. 相似文献
8.
Juliane Teller Barbara Natalie Unger Alexander Kock Hans Georg Gemünden 《International Journal of Project Management》2012
Companies frequently implement formalization to improve success. Previous research has found supporting evidence for the performance-enhancing effects of formalization in both single project management and project portfolio management. However, there is no research on how formalization at the project level interacts with formalization at the portfolio level, or on how this interaction may impact success. This study investigates the interaction of formalization at both levels and examines the moderating effect of project portfolio complexity on formalization. Using a sample of 134 firms, this study shows that single project management formalization and, likewise, portfolio management formalization are directly connected to portfolio success. Simultaneous formalization at these two levels delivers a complementary effect, resulting in an increase in success that is more than additive. A contingency analysis confirms that the proposed positive effects become more prominent if complexity is high. Complexity measured as project interdependency has a stronger moderating effect than complexity measured as portfolio size. 相似文献
9.
As increasing water shortages continue, water re-use is posing new challenges with treated wastewater becoming a significant source of non-potable water. Rapid detection strategies that target waterborne pathogens of concern to industry are gaining importance in the assessment of water quality. This study reports on the ability to recover spiked Cryptosporidium and Giardia from a variety of industrial wastewater streams of varied water quality. Incorporation of an internal quality control used commonly in finished water-enabled quantitative assessments of pathogen loads and we describe successful analysis of pre- and part-treated wastewater samples from four industrial sites. The method used combined calcium carbonate flocculation followed by flow cytometry and epifluorescence microscopy. Our focus will now aim at characterising the ambient parasites isolated from industrial wastewater with the objective of developing a suite of highly specific platform detection technologies targeted to industrial needs. 相似文献
10.
Among the seven assemblages identified in Giardia duodenalis species, only assemblages A and B infect humans and numerous other mammals as well. On the other hand, assemblage E is considered to be host restricted to livestock. The aim of the present study was to compare the presence of G. duodenalis assemblages A, B and E in wastewater samples from two municipal treatment plants (n=24) and one slaughterhouse (n=12). Thus, PCR assays targeting the tpi gene were developed to detect specifically these three G. duodenalis assemblages. Assemblages A and B were detected in urban wastewater with a predominance of assemblage A, especially for one treatment plant. Concerning slaughterhouse wastewater, assemblage A was found in 58% of the samples, whereas assemblage B was not detected. Assemblage E was not detected in urban wastewater, but was found in 92% of the samples from slaughterhouse. Thus, combination of assemblages A and B seemed to indicate a human contamination origin, while combination of assemblages A and E appeared to correspond to a livestock contamination origin. 相似文献
11.
Wood ash (3.1, 3.3 or 6.6 tonnes dry weight ha− 1) was used to fertilize two drained and forested peatland sites in southern Sweden. The sites were chosen to represent the Swedish peatlands that are most suitable for ash fertilization, with respect to stand growth response. The fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from the forest floor, measured using opaque static chambers, were monitored at both sites during 2004 and 2005 and at one of the sites during the period 1 October 2007-1 October 2008. No significant (p > 0.05) changes in forest floor greenhouse gas exchange were detected. The annual emissions of CO2 from the sites varied between 6.4 and 15.4 tonnes ha− 1, while the CH4 fluxes varied between 1.9 and 12.5 kg ha− 1. The emissions of N2O were negligible. Ash fertilization increased soil pH at a depth of 0-0.05 m by up to 0.9 units (p < 0.01) at one site, 5 years after application, and by 0.4 units (p < 0.05) at the other site, 4 years after application. Over the first 5 years after fertilization, the mean annual tree stand basal area increment was significantly larger (p < 0.05) at the highest ash dose plots compared with control plots (0.64 m2 ha− 1 year− 1 and 0.52 m2 ha− 1 year− 1, respectively). The stand biomass, which was calculated using tree biomass functions, was not significantly affected by the ash treatment. The groundwater levels during the 2008 growing season were lower in the high ash dose plots than in the corresponding control plots (p < 0.05), indicating increased evapotranspiration as a result of increased tree growth. The larger basal area increment and the lowered groundwater levels in the high ash dose plots suggest that fertilization promoted tree growth, while not affecting greenhouse gas emissions. 相似文献
12.
Microcystis colonies are known to overwinter on the surface of the sediment of freshwater ecosystems. However, little is known about the genotypic and toxicological dynamics of Microcystis populations during this benthic life stage. In this study, we report a two-year-long survey of benthic populations of Microcystis, which had spent from a few days to more than six years in the sediment. In order to avoid any interaction with the planktonic proliferations, we chose two deeply buried benthic populations, which could be easily dated. Quantitative PCR on mcyB gene and protein phosphatase inhibition assays were performed to measure their toxic potential, and their genotypic structure was assessed by Capillary Electrophoresis-Single Strand Conformation Polymorphism (CE-SSCP), based on 16S-23S Intergenic Transcribed Spacer (ITS). The microcystin content of the cells seemed to change sharply during the first few months of benthic survival, whereas this content was low and decreased steadily after several years of benthic life. No genetic selection was observed in either the proportion of potentially toxic clones or the ITS sequences for any of the populations considered. From these results, the benthic life stage of Microcystis appears to preserve the structure and the composition of the population over a far larger time scale than classical overwintering period. Finally, some genotypes were common in both of the benthic populations, even though they originated from planktonic blooms that had developed five years apart, suggesting a major overlap of planktonic proliferations in successive years. 相似文献
13.
Effects of soil type, irrigation volume and plant species on treatment of log yard run-off in lysimeters 总被引:1,自引:0,他引:1
Wet storage of timber and pulpwood produces large quantities of run-off water. A study was conducted to determine the purification efficiency of soil-plant systems for log yard run-off. Sixteen 1200-l lysimeters (1.2 m deep soil columns) with clay or sand soil were planted with willow (Salix sp.) or alder (Alnus glutinosa), and irrigated with run-off from a Norway spruce (Picea abies) log yard. Drainage water was analysed for total organic carbon (TOC), phenols, total P and total N in order to determine concentrations and levels of retention. High retention of TOC, phenols and P occurred in the lysimeters, but no clear differences between willows and alder or clay and sand were identified. Lysimeters with high levels of irrigation showed greater retention than those with low levels. Soil-plant systems using willow and alder could provide an alternative for log yard run-off purification: the key requirement is to optimise irrigation rather than manipulate the plants or soils. 相似文献
14.
Biochemical stress response in tetradifon exposed Daphnia magna and its relationship to individual growth and reproduction 总被引:1,自引:0,他引:1
M.J. Villarroel E. Andreu-Moliner M.D. Ferrando 《The Science of the total environment》2009,407(21):5537-5542
Environmental risk assessment of chemicals toxicity requires the use of costly and labor-intensive chronic data and short-term tests provide additional information. Energy budget is used by the animals for their growth, reproduction, and metabolism and it is reduced in case of toxic stress. Tetradifon acaricide is frequently used in the European Mediterranean region and it is implicated in aquatic environmental pollution. Previous studies showed that the EC50-24 h of tetradifon on Daphnia magna was 8.92 mg/L. Based on that, D. magna were exposed to sublethal tetradifon concentrations of 0.10, 0.18, 0.22 and 0.44 mg/L for five days in order to investigate their effect on intermediate metabolism. Caloric content was determined as biomarker of tetradifon toxicity. Results were analyzed using one-way analysis of variance (ANOVA) and Duncan's significant difference test was used to find differences between groups (α was set at p = 0.05). Daphnids energy content decreased as tetradifon concentration increased. At 120-h caloric content was depleted > 51% at pesticide concentrations of 0.18 mg/L and higher. In order to determine a possible link between the 5-d test and the 21-d chronic test, animals under short-term test were exposed to the same pesticide concentrations known to cause adverse effects on reproduction, growth and survival. Results from the present study indicated a good correlation between the proposed 5-day test and daphnid energy budget. Comparison between both, caloric content results and the chronic effect values obtained using life-table studies, suggested a good fit between them. These studies can be used as earlier, predictive and useful tests with comparable results to the classic chronic ones. Our results indicate that caution must be done about the use of tetradifon in the aquatic environment. 相似文献
15.
M. Gourmelon M.P. Caprais R. Marti N. Wéry M. Derrien P.Y. Communal A.M. Pourcher 《Water research》2010,44(16):4812-4824
The microbiological quality of coastal or river waters can be affected by faecal pollution from human or animal sources. An efficient MST (Microbial Source Tracking) toolbox consisting of several host-specific markers would therefore be valuable for identifying the origin of the faecal pollution in the environment and thus for effective resource management and remediation. In this multidisciplinary study, after having tested some MST markers on faecal samples, we compared a selection of 17 parameters corresponding to chemical (steroid ratios, caffeine, and synthetic compounds), bacterial (host-specific Bacteroidales, Lactobacillus amylovorus and Bifidobacterium adolescentis) and viral (genotypes I-IV of F-specific bacteriophages, FRNAPH) markers on environmental water samples (n = 33; wastewater, runoff and river waters) with variable Escherichia coli concentrations. Eleven microbial and chemical parameters were finally chosen for our MST toolbox, based on their specificity for particular pollution sources represented by our samples and their detection in river waters impacted by human or animal pollution; these were: the human-specific chemical compounds caffeine, TCEP (tri(2-chloroethyl)phosphate) and benzophenone; the ratios of sitostanol/coprostanol and coprostanol/(coprostanol+24-ethylcopstanol); real-time PCR (Polymerase Chain Reaction) human-specific (HF183 and B. adolescentis), pig-specific (Pig-2-Bac and L. amylovorus) and ruminant-specific (Rum-2-Bac) markers; and human FRNAPH genogroup II. 相似文献
16.
In this study, silver cations dissolved as silver nitrate at various concentrations were exposed to Legionella pneumophila, Pseudomonas aeruginosa, and Escherichia coli to quantitatively estimate the bactericidal ability of silver. Observed data were analyzed using a newly developed model (Cs x T) that introduced a specific amount of chemisorbed silver onto a bacterial cell (Cs), which represented the chemisorption properties of silver on the bacterial cell body. Silver cations were rapidly chemisorbed onto bacterial cells after injection into samples, and Cs values (initial concentration of silver was 0.1 mg Ag/l) were calculated as 1.810 x 10(-6) (L. pneumophila), 1.102 x 10(-6) (P. aeruginosa), and 1.638 x 10(-6) microg Ag/cell(i) (E. coli) after incubation for 8 h. During that time, the three tested bacteria were completely inactivated under the detection limit (>7.2 log reduction). Based on the calculated Cs values, bacterial tolerance against silver was estimated by using the equation (Cs x T) multiplying the Cs values with exposure time (T). The Cs x T values well represented the bactericidal abilities of silver against the tested bacteria. The demanded Cs x T values to accomplish a 1 log inactivation (90% reduction) of L. pneumophila, P. aeruginosa, and E. coli (the initial numbers of bacteria were 1.5 x 10(7) CFU/ml, approximately) were estimated as 2.44 x 10(-6), 0.63 x 10(-6), and 0.46 x 10(-6) microgh/cell(i) of silver. The values were significantly reduced to 1.54 x 10(-6), 0.31 x 10(-6), and 0.25 x 10(-6) microgh/cell(i), respectively, with simultaneous injection of silver and copper. This study shows the successful quantitative estimation of the bactericidal ability of silver by applying the newly developed model (Cs x T). Among the tested bacteria, L. pneumophila showed the strongest tolerance to exposure of the same concentration of silver. 相似文献
17.
Lemus JA Bravo C García-Montijano M Palacín C Ponce C Magaña M Alonso JC 《The Science of the total environment》2011,409(22):4729-4734
For many years anticoagulant rodenticides have been used in vole control campaigns, in spite of the proven risk of secondary poisoning of non-target predators and scavengers. In this paper we analyse for the first time great bustard exposure and intoxication by anticoagulant rodenticides in Spain, based on residues found in the livers of 71 bustard carcasses collected during 1991-2010. Ten individuals contained chlorophacinone and one flocoumafen. Chlorophacinone level was significantly correlated with the pathogen and parasite burden of intoxicated birds. Moreover, through the last 12 years the annual number of great bustards that present chlorophacinone in liver collected in our study areas was correlated with vole peaks at a nearby area, suggesting that the ingestion of rodenticide was proportional to the amounts spread in the fields. We conclude that rodenticide consumption is a regular event among great bustards when baited cereal is spread on fields, and that this may cause chronic weakening of intoxicated individuals, possibly affecting their survival. Future rodent control actions should consider these negative side effects on non target granivorous steppe and farmland species, particularly when they are globally threatened. 相似文献
18.
Artificial recharge of groundwater through sprinkling infiltration: Impacts on forest soil and the nutrient status and growth of Scots pine 总被引:1,自引:0,他引:1
Pekka Nöjd Antti-Jussi Lindroos John Derome Heljä-Sisko Helmisaari 《The Science of the total environment》2009,407(10):3365-3371
We studied the chemical changes in forest soil and the effects on Scots pine trees caused by continuous sprinkling infiltration over a period of two years, followed by a recovery period of two years. Infiltration increased the water input onto the forest soil by a factor of approximately 1000. After one year of infiltration, the pH of the organic layer had risen from about 4.0 to 6.7. The NH4-N concentration in the organic layer increased, most probably due to the NH4 ions in the infiltration water, as the net N mineralization rate did not increase. Sprinkling infiltration initiated nitrification in the mineral soil. Macronutrient concentrations generally increased in the organic layer and mineral soil. An exception, however, was the concentration of extractable phosphorus, which decreased strongly during the infiltration period and did not show a recovery within two years. The NO3-N and K concentrations had reverted back to their initial level during the two-year recovery period, while the concentrations of Ca, Mg and NH4-N were still elevated. Nutrient concentrations in the pine needles increased on the infiltrated plots. However, the needle P concentration increased, despite the decrease in plant-available P in the soil. Despite the increase in the nutrient status, there were some visible signs of chlorosis in the current-year needles after two years of infiltration. The radial growth of the pines more than doubled on the infiltrated plots, which suggests that the very large increase in the water input onto the forest floor had no adverse effect on the functioning of the trees. However, a monitoring period of four years is not sufficient for detecting potential long term detrimental effects on forest trees. 相似文献
19.
The use of isotopic and lipid analysis techniques linking toluene degradation to specific microorganisms: applications and limitations 总被引:5,自引:0,他引:5
Phospholipid fatty acid (PLFA) analysis combined with (13)C-labeled tracers has been used recently as an environmental forensics tool to demonstrate microbial degradation of pollutants. This study investigated the effectiveness and limitations of this approach, applied to the biodegradation of toluene by five reference strains that express different aerobic toluene degradation pathways: Pseudomonas putida mt-2, P. putida F1, Burkholderia cepacia G4, B. pickettii PKO1, and P. mendocina KR1. The five strains were grown on mineral salts base medium amended with either 10 mM natural or [(13)C-ring]-labeled toluene. PLFA analysis showed that all five strains incorporated the toluene carbon into membrane fatty acids, as demonstrated by increases in the mass of fatty acids and their mass-spectrometry fragments for cells grown on (13)C-labeled toluene. Because of its ubiquitous presence and high abundance in bacteria, C16:0 fatty acid might be a useful biomarker for tracking contaminant degradation and (13)C flow. On the other hand, the (13)C-label (which was supplied at relatively high concentrations) generally exerted an inhibitory effect on fatty acid biosynthesis. Differences in fatty acid concentrations between cells grown on natural versus (13)C-labeled toluene would affect the interpretation of lipid profiles for microbial community analysis as indicated by principal component analysis of fatty acids. Therefore, caution should be exercised in linking lipid data with microbial population shifts in biodegradation experiments with (13)C-labeled tracers. 相似文献
20.
In situ characterization of nitrifying biofilm: Minimizing biomass loss and preserving perspective 总被引:1,自引:0,他引:1
Methods for characterizing nitrifying bacteria within biofilms are of key importance to understand and optimize the nitrification kinetics of attached growth treatment facilities. In this work, we propose an analytical protocol based upon environmental scanning electron microscopy (ESEM) and confocal laser scanning microscopy (CSLM) in combination with fluorescent in situ hybridization (FISH) to characterize the structure of nitrifying biofilm as it remains attached to the original reactor substratum. This protocol minimizes the loss of mass and distortion of in situ perspective commonly associated with traditionally applied microscopic techniques and thereby enables a more accurate estimation of the nitrifying biomass within biofilm attached to the substratum. The use of ESEM eliminates the destructive preparatory procedures associated with traditional scanning electron microscopy and thus the loss of mass and shrinking of the samples. ESEM is used in this study to evaluate the percent coverage of the substratum with biofilm and the biofilm thickness. CLSM-FISH is used to determine cell counts in the biofilm and to characterize the undisturbed substratum/biofilm interface. By hybridizing and analyzing the nitrifying biofilm using CLSM as it remains attached to the substratum, the loss of material and distortion of in situ perspective associated with the biofilm detachment process is minimized. Moreover, by conducting the CLSM analysis directly on the nitrifying biofilm as it remains attached to the substratum it is shown that cell counts at the substratum/biofilm interface differ significantly from that located above the interface. 相似文献