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131.
Hartmut Frank Harald Scholl Dirk Renschen Benoît Rether Abdelkrim Laouedj Yrjö Norokorpi 《Environmental science and pollution research international》1994,1(1):4-14
Haloacetic acids are atmospheric oxidation products of airborne C2-halocarbons which are important solvents and propellants. Levels of trichloroacetate (TCA) in conifer needles from mountain
ranges in Germany (Black Forest, Erzgebirge) and from two sites in Finland are compared; TCA is present in conifer needles
at concentrations up to 0.7 μmol/kg, MCA up to 0.2 μmol/kg. At the Finnish sites, TCA-concentrations and branch degeneration
symptoms of Scots pine are correlated. Monochloroacetate (MCA) has been determined in needle samples from Southern Germany
in concentrations exceeding its phytotoxicity threshold towards photoautotrophic organisms. Data on atmospheric chloroacetate
levels in Germany are also given; ambient air levels of chloroacetic acids range from about 2 pmol/m3 (TCA) to 390 pmol/m3 (MCA). TCA and dichloroacetic acid (DCA) arise from atmospheric oxidation of airborne C2-chlorocarbons, while the source of MCA is not yet known; several tentative pathways are suggested. 相似文献
132.
A design and application of a multi-agent system for simulation of multi-actor spatial planning 总被引:13,自引:0,他引:13
Ligtenberg A Wachowicz M Bregt AK Beulens A Kettenis DL 《Journal of environmental management》2004,72(1-2):43-55
Multi-agent Systems (MAS) offer a conceptual approach to include multi-actor decision making into models of land use change. The main goal is to explore the use of MAS to simulate spatial scenarios based on modelling multi-actor decision-making within a spatial planning process. We demonstrate MAS that consists of agents representing organizations and interest groups involved in an urban allocation problem during a land use planning process. The multi-actor based decision-making is modelled by generating beliefs and preferences of actors about the location of and relation between spatial objects. This allows each agent to confront these beliefs and preferences with it's own desires and with that of other agents. The MAS loosely resembles belief, desire and intentions architecture. Based on a case study for a hypothetical land use planning situation in a study area in the Netherlands we discuss the potential and limitations of the MAS to build models that enable spatial planners to include the 'actor factor' in their analysis and design of spatial scenarios. In addition, our experiments revealed the need for further research on the representation of spatial objects and reasoning, learning and communication about allocation problems using MAS. 相似文献
133.
134.
Zusammenfassung Mit einem Bioaktivit?tssensor kann die Aktivit?t der Mikroorganismen im Belebtschlamm gemessen werden. Das Signal des Sensors
reagiert empfindlich auf eine Ver?nderung des Substratangebots und das Auftreten von toxischen Stoffen. Mit dem Bioaktivit?tssensor
ist es damit einerseits m?glich,online die Belebungsstufe hinsichtlich ihrer mikrobiellen Aktivit?t zu kontrollieren und andererseits die zuflie?enden Abw?sser
bezüglich ihres toxischen Potentials zu überwachen.
相似文献
135.
Dirk F. Wenderoth Petra Rosenbrock Dietmar Pieper Manfred G. Höfle 《Water, Air, & Soil Pollution: Focus》2002,2(3):195-203
A set of microcosm experiments was performed to understand the behaviour of special degraders in bioaugmentation experiments. In the experiments the following chlorobenzene degraders were used: the genetically modified Pseudomonas putida F1CC, and the two wild-type strains Pseudomonas putida GJ31 and Pseudomonas aeruginosa RHO1. These strains were used at an initial cell density of 105 cells mL–1 groundwater which had been spiked with 1,2-dichlorobenzene (1,2-DCB), 1,4-dichlorobenzene (1,4-DCB) and, as main contaminant, chlorobenzene (CB). The population dynamics and behaviour of the three special degraders within the groundwater microcosms were studied by single-strand conformation polymorphism (SSCP) analysis of 16S rDNA fragments amplified from directly extracted community DNA and fluorescent in situ hybridization (FISH) with species-specific probes. RHO1 disappeared after 4 days as detected by FISH in contrast to SSCP-detection where RHO1 could be found during the whole incubation time. Whereas GEM F1CC and wild-type strain GJ31 survived the whole incubation for 20 days. With both methods we were able to detect all strains with high specificity among the indigenous microbial community. The data sets obtained from SSCP analysis and FISH were highly correlated. Specific band intensity within the SSCPfingerprints and the cell counts determined by FISH gave a quantitative overview about the introduced strains. 相似文献
136.
This article describes the application of in-situ bioremediation for the treatment of an aquifer contaminated with 1,2-dichloroethane (DCA). The first step in the process was to properly delineate the contamination and to contain the contaminated groundwater using a pumping well. The second step was to isolate in the groundwater microorganisms able to degrade DCA and to demonstrate the possibility of increasing their efficiency by injecting in-situ nutrients and hydrogen peroxide (H2O2) solution. In the third step, after the characterization of the hydrogeology of the aquifer with tracing experiments, the in-situ bioremediation of the groundwater was conducted. The analyses show that 95 percent of DCA was destroyed by this treatment, leading to a DCA concentration around the pumping well of about 0.2 mg/l. 相似文献
137.
138.
We investigated the phylogenetic relationships among different size groups of the pelagic microcopepod Oncaea venusta Philippi, 1843, by comparing the patterns of genetic variation of specimens collected at five locations of the Indo-West Pacific Ocean. Phylogenetic analyses were based on sequence data obtained from two DNA markers: A 310 bp fragment of the mitochondrial cytochrome b (cyt b) gene and a 480 bp fragment of the nuclear internal transcribed spacer 1 (ITS1). The cyt b sequences showed a much higher level of variation than those from ITS1, but the conclusion from both genes was concordant. Four genetic clades could be differentiated. A small- and a large-size group were unambiguously assigned to two distinct clades or lineages. Unexpectedly, the medium-sized individuals could be divided into another two different genetic clades. All four lineages were supported by high bootstrap values. The high levels of sequence divergence under sympatric conditions indicated that at least the two main groups, the large and the small one, may be assigned to different species. For the medium-size group additional morphological studies and more sensitive nuclear markers are required to clarify their taxonomic status. 相似文献
139.
Biphenyl degrading bacteria (40 strains) have been isolated along a gradient of chlorobenzene pollution from an aquifer which did not contain any PCB to answer the question of how metabolic/catabolic abilities exist in ecosystems that have not been stressed with the relevant substrates is important for intrinsic bioremediations. Only few of the isolates were characterized by 16S rRNA gene sequence analyses as Pseudomonas species while the majority were Gram-positive, belonging to the order Actinomycetales and representing the genera Rhodococcus and Arthrobacter. The strains could grow on a variety of chlorobenzoates but no pattern of substrate usage and phylogeny or pollution gradient could be found. Strains which were able to grow on 2,5-dichlorobenzoate were often also able to use 3,4- and 3,5-dichloro- and 2,3,5-trichlorobenzoate or those using 2-chlorobenzoate could usually use 2,6-dichlorobenzoate as well. From that results, it is concluded that a highly diverse, basic metabolic activity for PCB degradation existed at this site despite the absence of PCB. 相似文献
140.
Biesmeijer JC Giurfa M Koedam D Potts SG Joel DM Dafni A 《Die Naturwissenschaften》2005,92(9):444-450
Several recent hypotheses, including sensory drive and sensory exploitation, suggest that receiver biases may drive selection
of biological signals in the context of sexual selection. Here we suggest that a similar mechanism may have led to convergence
of patterns in flowers, stingless bee nest entrances, and pitchers of insectivorous plants. A survey of these non-related
visual stimuli shows that they share features such as stripes, dark centre, and peripheral dots. Next, we experimentally show
that in stingless bees the close-up approach to a flower is guided by dark centre preference. Moreover, in the approach towards
their nest entrance, they have a spontaneous preference for entrance patterns containing a dark centre and disrupted ornamentation.
Together with existing empirical evidence on the honeybee's and other insects’ orientation to flowers, this suggests that
the signal receivers of the natural patterns we examined, mainly Hymenoptera, have spontaneous preferences for radiating stripes,
dark centres, and peripheral dots. These receiver biases may have evolved in other behavioural contexts in the ancestors of
Hymenoptera, but our findings suggest that they have triggered the convergent evolution of visual stimuli in floral guides,
stingless bee nest entrances, and insectivorous pitchers. 相似文献