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1.
The biochemical basis for resistance to metal ion toxicity is emerging though it is complicated by the different resistance mechanisms. Several strategies for resistance to toxic metal ions have been identified:
  1. The development of energy driven efflux pumps which keep toxic element levels low in the interior of the cell. Such mechanisms have been described for Cd(II) and As(V).

  2. Oxidation (e.g. AsO2‐ to AsO4 3‐) or reduction (e.g. Hg2+ to Hg0) can enzymatically and intracellularly convert a more toxic form of an element to a less toxic form.

  3. The biosynthesis of intracellular polymers which serve as traps for the removal of metal ions from solution such as traps have been described for cadmium, calcium, nickel and copper.

  4. The binding of metal ions to cell surfaces.

  5. The precipitation of insoluble metal complexes (e.g. metal sulfides and metal oxides) at cell surfaces.

  6. Biomethylation and transport through cell‐membranes by diffusion controlled processes.

In this short review I shall discuss the implications of biomethylation as a detoxification mechanism for microorganisms as well as for certain higher organisms.  相似文献   

2.
Anaerobic fluidised bed reactor is an instrument very much adapted in the experimental study of the kinetics of the complex biological process. In this experimental work the efficiency of the treatment of an anaerobic fluidised bed reactor with immobilised cells is examined in transition phase. The results of the experiments can be summarised as follows:
  • a zero order elimination rate of the substrate is presented;

  • the order of the reaction changes after a period of significant substrate elimination and follows a homographic equation

  • the non‐dissociated part of the substrate ions is degradable.

  相似文献   

3.
Aluminium is the most-used metal in the world after steel, with a wide range of applications in the industrial field owing to its physical and mechanical properties. The aim of this study was environmental and economic analysis of secondary aluminium. In particular, this study demonstrated that aluminium recycling offers many advantages to both consumers and industry:
  • Increased energy savings compared to primary aluminium production;

  • Recovery and reuse of raw materials for future production avoids consumption of non-renewable resources;

  • Reduction in landfill waste and consequent environmental damage;

  • Reduction in bauxite mining which, in turn, will reduce the socio-economic impact on populations of those countries, mainly underdeveloped, that contain mines;

  • Economic advantages for Italy, the first European producer of secondary aluminium, which lacks bauxite mines and has high energy costs.

This study used the Life Cycle Assessment (LCA) method, the modified Eco-indicator 99 method for damage calculation, and the SimaPro calculation code. The study examined secondary aluminium production by ICMET, based in Reggio Emilia, Italy. The economic and environmental evaluation utilised environmental information supplied by the company.  相似文献   

4.
During acute oral intoxication by cadmium compounds, gastrointestinal epithelial damage contributes to immediate toxicity. However, secondary systemic toxicity may develop due to intestinal uptake of cadmium. This review presents an evaluation of the effects of chelators on the acute toxicity of cadmium after parenteral or oral exposure and on the intestinal uptake of cadmium. This review shows:
  1. Chelating agents may affect the acute toxicity of cadmium in a variety of ways depending on the exposure route for cadmium and administration route for the chelator.

  2. With regard to survival, systemic toxicity of absorbed cadmium is of major importance, as intraperitoneal administration of chelators could eliminate or reduce mortality due to orally administered cadmium chloride.

  3. Lipophilicity of chelators and their cadmium complexes may result in extensively augmented intestinal uptake. However, hydrophilic chelators may efficiently reduce the intestinal cadmium uptake.

  4. For hydrophilic chelators, the stability of the cadmium complex is an important determining factor of efficacy.

  5. The optimal oral antidote towards orally administered cadmium are the BAL analogs, especially DMSA, while the optimal intraperitoneal antidotes towards orally or intraperitoneally administered cadmium are the higher members of the polyaminopolycarboxylate family, especially TTHA.

  6. When administered simultaneously (DMSA orally and TTHA intraperitoneally), these chelators synergistically reduce the whole‐body retention of cadmium.

In conclusion, chelation treatment in acute oral cadmium intoxication should first prevent/reduce intestinal damage and uptake by rapid oral administration of a chelating antidote and then alleviate systemic toxicity due to absorbed cadmium and enhance renal/biliary cadmium excretion by parenteral administration of a chelating antidote.  相似文献   

5.
《毒物与环境化学》2012,94(3-6):165-189
Abstract

Titanium dioxide nanoparticles (nano-TiO2) are useful because of their unique physicochemical properties. The wide application of nano-TiO2 has raised concerns regarding its potential threat to organisms and the environment. Therefore, the production and application of nano-TiO2 in the global market is summarized in this paper. This review presents the adverse effects of nano-TiO2 in vivo, including potential exposure routes such as transdermal, oral and inhalative exposure, risk evaluation of nanotoxicity in vitro using bacteria, microorganisms, cells and biological molecules), physicochemical characterization of nano-TiO2 regarding crystal structure, size, shape, surface characteristics and coatings, and the mechanisms of toxicity of nano-TiO2 based on environmentally relevant test species and cells. This review aims to fill deficiencies in toxicological research and to facilitate the assessment of the environmental risks by nano-TiO2 which is conducive to designing safer nanoproducts in our daily life.
  • Highlights
  • Presented the possible human health hazards related to nano-TiO2 exposure.

  • Identified the current research deficiencies in this area.

  • Summarized the underlying toxicity mechanisms.

  • Summarized the compound toxicity of NPs.

  相似文献   

6.
7.
The biochemical speciation of chromium compounds in mammalian cells is discussed with respect to uptake, metabolism, DNA binding and damaging. Whereas soluble hexavalent chromium is taken up rapidly and accumulated intracellularly after its reduction, compounds of trivalent chromium penetrate biomembranes about three orders of magnitude slower. Cr(VI) after its uptake is metabolised by electron donating compounds via Cr(V) to Cr(III) compounds. Chromium from various Cr(III) compounds, but not chromate, binds to chromatin in isolated cell nuclei. The DNA‐protein crosslinks and DNA strand breaks observed in rat liver and kidney after chromate administration are also found in vitro, when Cr(III) compounds (but not chromate) interacts with isolated nuclei. In the Chinese Hamster cell HGPRT mutation assay, three out of four tested Cr(III) complexes were found to be mutagenic. In a direct DNA strand break assay with supercoiled bacteriophage PM 2 DNA, neither chromate nor the four Cr(III) compounds tested caused nicks. However, the combined action of chromate plus glutathione as well as the isolated complex of pentavalent chromium, Na4Cr(glutathione)4, did cause DNA breaks. Reactive oxygen species are inferred to be the ultimate DNA nicking agents in this assay. In conclusion there appear to be two mechanisms of chromate genotoxicity; one with direct DNA damage caused by Cr(V) species and one via DNA‐protein crosslinks formed with Cr(III), the final reduction state of chromate.  相似文献   

8.
The scope of anaerobic metabolism of Sipunculus nudus L. was assessed from the maximal activities of some enzymes of the intermediary metabolism and from the concentration of some metabolites accumulated during enhanced muscular activity and during prolonged experimental hypoxia.
  1. Maximal enzyme activities demonstrate that the scope of anaerobic glycolysis, as indicated by maximal activities of glycogen phosphorylase (0.84 U g-1 fresh wt), far exceeds the aerobic capacity, which is assumed not to surpass the activity of succinate dehydrogenase (0.09 U g-1 fresh wt). Three pyruvate reductase activities (alanopine-, strombine- and octopine dehydrogenase) can possibly terminate anaerobic glycolysis.
  2. During muscular activity, energy is provided by the degradation of phospho-L-arginine and by anaerobic glycolysis. Octopine is the major endproduct during functional anaerobiosis while the formation of strombine is less pronounced.
  3. During exposure to a nitrogen atmosphere, several anaerobic endproducts are found to accumulate. Anaerobic glycolysis is terminated by strombine synthesis. This opine accumulates in concentrations much higher than octopine. In addition the concentrations of succinate, propionate and acetate are found to increase in tissues, and/or in the coelomic fluid and the incubation water.
  4. The relative contribution of energy by the different anaerobic metabolic pathways are estimated during functional and environmental hypoxia.
  相似文献   

9.
Ecotoxicological investigations focus on biological systems and their response to chemically induced stress. Experimental techniques are much more developed than deterministic dynamic modelling. In this methodological contribution a technique is presented, based on lattice theory. This technique, also calledHasse diagram technique, allows data analysis with respect to comparative evaluation. Hasse diagrams are used
  • ? to suggest a possible measure of microbial diversity,
  • ? to analyze dependencies between phospholipid fatty acids and simple geochemical parameters on an ordinal scale and
  • ? to visualise complex results of interactions of humic substances with xenobiotics.
  •   相似文献   

    10.

    Background

    Sorting and disposal of waste are the last steps in the “lifetime” of a product. If products are contaminated with chemicals assessed to be hazardous for man or environment, waste management has the role of a vacuum cleaner in substance chain management working in two different ways: The hazardous compounds have to be properly separated from potential secondary resources in sorting processes. If this is not possible, those products have to be disposed safely. Starting from the experiences collected with some chemicals banned, the tools used for phasing out these chemicals from the technosphere are studied with respect to their influence on the contamination of the environment.

    Results

    Even if a dangerous substance has been banned, it is further used in a number of products. In the cases presented here, the substances were banned for further use. In the case of CFCs, the substitutes used have partially also been substituted because of adverse effects. Besides the prohibition of use of hazardous substances, numerous other regulations were issued to reduce unsafe handling and minimize emissions into the environment. It turned out that waste management cannot correct mistakes which already happened “upstream” in the product chain. The control of point sources works quite successfully, whereas today the overwhelming emissions stem from diffuse sources, partially caused by unsafe waste management procedures.

    Conclusions

    Though there are no complete balances for both groups of compounds serving as examples, some conclusions can be drawn based on the experiences collected. Hazardous compounds may be separated successfully from used products or waste,
    • If they are mostly used in industry and not in households,
    • if they can be identified as part of certain products,
    • if their concentration in these products is rather high,
    • if technical problems come up when they contaminate secondary raw materials,
    • if there is international support for proper waste management.
      相似文献   

    11.
    For the time being, simple and reliable methods which permit the imaging of the complex topography of contaminant plumes in groundwater are missing. The conventional methods for the punctual determination of contaminant concentrations cannot fulfill this demand. To successfully implement and utilize. Natural Attenuation, these deficits have to be overwhelmed. The detectors described in the following represent only part of the probing device system the authors have developed; it shall enable their user to image different aspects of plume topography and its time dependent change by monitoring within the undisturbed groundwater aquifer in groundwater measuring levels:
  • ? relative freights of contaminants and trace contaminants by passive samplers [4] and
  • ? redox milieu parameters by detectors.
  • The detectors offer multi-purpose, tape-like probing devices of unlimited length. They are charged with a defined reserve of reactive substances. During monitoring actions, the derector tape hangs vertically stretched by a weight preferably covering from the top to the bottom of the whole water column. During the reaction period, the detector may be relaunched for repeated visual inspection. The colour changes of the detectors enable the identification of a row of parameters in the vertically (depth-) oriented profile by unbroken optical/visually perceivable imaging:
  • ? Position of Redox potential thresholds for Mn-IV-Mn-II, Fe-III-Fe-II, Sulfate-Sulfide
  • ? Position of ochre precipitation and iron-sulfide precipitation horizons
  • ? Relative freights of the sum of substances effecting reduction (period until defined oxidant reserve has been reduced)
  • ? Relative freights of the sum of substances effecting iron-sulfide oxidation (period until defined reductant reserve has been reduced)
  • ? Position of dissolved iron-II ions containing horizons
  • ? Position of dissolved hydrogen-sulfide ions/hydrogen-sulfide containing horizons
  • ? Relative freights of iron-II ions (period until defined oxidant reserve has been reduced)
  • ? Relative freights of hydrogen-sulfide ions/hydrogen-sulfide (period until defined oxidant reserve has been reduced). Furthermore, the detectors are also suitable for the examination of waters even of great depth, as for example artificial or natural lakes, sea and ocean basins.
  •   相似文献   

    12.

    Aim and Scope

    This study was aimed at evaluating environmental effects of tar-oil impregnated (tanalized) tree stakes using simple and efficient biotests to obtain results of its ecological impacts during the tar-oil breakdown in the stake.

    Results

    1. Soil respiration was measured in-situ as an indication of soil microbial activity in two field trials. Soil respiration was measured in a 20 year-old apple orchard at various distances from the tar-oil impregnated tree stakes and also on soil mixed with chippings from pine stakes with tar-oil impregnation of different ages.
    2. Cress germination tests were employed to evaluate tar-oil phytotoxicity in a field and laboratory trial. Cress was seeded close to tree stakes in the same 20 year-old apple orchard and germination rates related to tar oil-impregnation. Cress was also seeded in trays in sand mixed with pine chippings from stakes with tar-oil impregnation of different ages.
    3. The portion of the carcinogenic benzoapyrene (BaP) ranged between 0.0015% in freshly tar-oil impregnated to 0.4% in tar-oil impregnated 20-year old trees stakes, i.e. irrespective of the overall PAK concentration and its degradation.
    4. Kinetic analysis using DIXON plots showed a 50% breakdown of overall PAHs after ca. 2.7 years, i.e. km or Ki values of less than 3 years.

    Conclusion

    Germination tests of cress and endogenous seeds as well as soil respiration proved sensible indicators of the phytotoxicity and ecotoxicity of tar-oil impregnated tree stakes in fruit orchards. Soil respiration proved particularly sensitive to tar-oil ageing. Its combination with kinetic inhibition models resulted in parameters suitable for the interpretation of results.  相似文献   

    13.
    This paper reviews the environmental problems associated with the coal-mining industry on the Yorkshire coalfield. The main environmental problems are identified as being caused by:
    1. The need to dispose of large quantities of colliery waste or ‘spoil’, in an environmentally acceptable manner.
    2. Derelict and despoiled land, including the problems caused by the re-working of old tips for their coal content.
    3. Opencast coal mining.
    4. Subsidence.
    5. Transportation of coal and coal waste.
    These problems are reviewed in the context of the role of coal in meeting the United Kingdom's energy needs and the framework of environmental control within which the coal-mining industry has to operate. Particular stress is laid on the fact that the Yorkshire coalfield, as with the majority of coalfields, is an old one with a legacy of inherited dereliction. Whilst modernisation of the mining industry is proceeding there have not been parallel developments put in hand to cope with the changing nature of the environmental problems resulting from the modernisation of the industry. Particular stress is placed on the need to dispose of the greatly increased quantities of spoil now being produced.  相似文献   

    14.

    Background

    The analysis of the intrinsic effects of perfluorinated organic surfactants shows the group to have a characteristic overall picture:
  • -high polarity
  • -high thermal and chemical stability
  • -ubiquitous distribution
  • -non-biodegradability
  • -multiple toxicity
  • In addition, certain substances belonging to this group (e.g. PFOS) exhibit a very long retention time in the human body. Toxic properties vary and, like the mechanisms for global distribution, have not been fully clarified. In the meantime, individual members of this substance group have been (are being) removed from the market. This report shows that in future the planned EU chemicals law (REACH) can be used to prevent such substances being regulated after they have been distributed in the environment and thus after damage has already occurred. To this end, however, the requirements for registration for low tonnage substances (1–10 tonnes/a) must be supplemented with specific tests (in particular on biodegradability)

    Aim and Scope

    The aim of the work was to analyse the intrinsic properties and risks of a subgroup of fluorinated organic substances.

    Results

    A summarising article describes the toxic effects and properties of a group of substances selected from the approximately 30,000 existing substances. With regard to the ongoing debate on revising the European regulations of existing substances (REACH). it is apparent that standardised test requirements cannot be applied to impact and risk analyses which are at times highly complex. For governments, REACH only provides the starting points for this process in the form of prescribed standard tests. If a substance (or a substance group) draws attention, more detailed tests must be carried out by the industry itself in the framework of responsible care and in the framework of the evaluation step of REACH. It is therefore important that the standard requirements of REACH are selected appropriately. In this respect, the study reveals some serious deficiencies in the Commission proposal.

    Conclusion

    The standard information for low tonnage substances (1–10 tonnes/a) must be supplemented in particular with an obligatory test on biodegradability. The possibility provided by the REACH dossier to evaluate substances on the basis of group observarions (SAR, QSAR e.g.) is to be welcomed.  相似文献   

    15.

    Background and aim

    Air pollution caused by oxidized and reduced nitrogen is distributed over wide areas of Europe at a high level. As an alternative or complement to physical measurements and modelling calculations, biomonitoring with plants provides techniques to assess amounts and effects of pollution from oxidized and reduced nitrogen compounds (depositions and concentrations). Many of the previously implemented techniques are based on well-proven standardised methods, e.g. documented in VDI guidelines, modified more or less for a biomonitoring of atmospheric nitrogen pollution. This paper gives a review of the techniques for a biomonitoring of atmospheric nitrogen pollution, their possibilities as well as their limitations.

    Main features

  • -diversity of the ground vegetation
  • -nitrogen accumulation in vascular plants
  • -exposure of vascular plants
  • -mapping of epiphytic lichens, bryophytes and algae
  • -nitrogen accumulation in lichens and bryophytes
  • -exposure of lichens and bryophytes
  • Results and Discussion

    Important response parameters are nitrogen concentrations in plant tissue (shoot, needle, leave) and biodiversity of plant species. These responses of vascular plants in many cases are influenced by other local varying conditions, in particular the soil. The exposure of vascular plants over a short period provides a standardised quantification of the total atmospheric nitrogen input in a model ecosystem. The enrichment of nitrogen in the plant tissue of bryophytes and lichens from the ground vegetation is closely correlated with the amount of nitrogen deposition. The diversity of epiphytic lichens and the response of exposed Hypogymnia physodes is more sensitive to ammonia than to nitrous oxide, whereas with the diversity of epiphytic bryophytes or the abundance of algae no significant correlation with atmospheric N pollution were found.

    Conclusions

    Some bioindication techniques provide a causeeffect related, partly standardised biomonitoring of nitrogen pollution. In some cases varying experiences with some biomonitors like the biodiversity of the ground vegetation, exposure of lichens, moss bags and grass cultures stress the need for more research in this subject.  相似文献   

    16.
    For the two biosphere-reserves of Schorfheide-Chorin and Spreewald in the Federal State of Brandenburg, Germany, we designed a concept for a monitoring program of ecosystems which is feasible and inexpensive, and whose methodical development is transferable to other large-scale protected areas. Beside the statistical analysis of hard GIS data, we systematically used additional criteria such as naturalness, scarcity and special management, a based on expert knowledge. Thus, after an inventory of the existing ecosystems, we selected the ecosystems to be monitored from the different ecosystem groups (i.e. woods and forests, fens, lakes, rivers, arable land and grasslands) based on the following four criteria:
    1. dominance,
    2. naturalness,
    3. nation-wide scarcity and
    4. special management.
    We then combined the selected ecosystems with their relevant forms of landuse to so-called ecosystem-landuse-complexes, which reflect the natural conditions as well as the human impact in the biosphere reserves. This paper presents the selection of the ecosystem landuse complexes to be monitored. Thus, for both biosphere reserves, we obtained 32 ecosystem landuse complexes in woods and forests, 32 in fens, 53 in lakes, 7 in rivers, 23 in grasslands and 20 in arable land.  相似文献   

    17.
    The reclamation of tailing that is toxic to vegetation (phytotoxic) was the subject of laboratory and field research. Using trona tailing as an example of phytotoxic waste, research identified three areas that may be critical to reclamation:
  • establishment and maintenance of a capillary barrier to prevent upward migration of plant toxicants into the plant-rooting zone;
  • water drainage or evaporation to prevent or control water accumulation within the tailing;
  • soil requirements for revegetation.
  • A pilot reclamation program was developed in which a 20-cm layer of coarse gravel formed a capillary barrier between phytotoxic tailing and overlying material. To maintain the integrity of the capillary barrier, a 20-cm layer of fine gravel was applied to the coarse gravel surface; soil was then applied to the fine gravel surface. A zone of shallow soil was used to allow water, which collected during the late winter, to evaporate from the tailing during the dry summer. Soil depth requirements were assessed by measuring the response of shrubs and grasses to increasing soil depth.  相似文献   

    18.
    19.

    Goal, Scope and Background

    Worldwide energy requirements are constantly increasing. Rising prices and the necessity to secure the future energy supply have led the decision-makers in politics and economy to focus on the more intensive use of their own resources. Before the background of possible climatic effects caused by the use of fossil energies, the use of renewable resources as primary energies, with its narrow C-circulation, have gained in importance, particularly in terms of economic aspects. The production of biogas is of specific interest here. It is a sensible ecological investment and a solid source of income for our agriculture.

    Material and Methods

    The operator uses a complex biological system in a plant with high investment costs. An economic operation is only possible if the process parameters are optimized and the properties of the substrates and the co-ferments are known. For the important determination of the blogas potential, we present an efficient and robust system, which is easy to handle and low cost, that has been developed by the LHL and LLH at the Eichhof. This procedure enables one to make statements on the implementation dynamics and is also suited to judge the fermentation process depending on the size of particles, as the co-ferments are used in a practice-oriented consistency.

    Results

    With the described fermentation apparatus you can not only assess the potential development of biogas and methane, but also the process of fermentation. The sum-graphs determined allow one to make conclusions on the implementation dynamics and, thus, on the optimization of the process. The advanced equipment makes it possible to determine the process of fermentation and the gas yield under different retention times and digester loads. The determination of the potential of the biogas and also the evaluation of the continuous fermentation are related to a specific correction factor won from the standard.

    Discussion

    A prerequisite for economic process management is the knowledge of the attainable gas yield and the fermentation process of substrates and co-ferments. A precise calibration is the quality basis for the results achieved with this method, as is the case with other fermentation tests as well. For the tests, a highly homogeneous substrate, which guarantees a continuous biological activity in the digesters, ought to be used. The possibility of determining optimum retention times and digester loads with this equipment makes costly tests with a full scale reactor unnecessary.

    Conclusions

    All tests run demonstrated that the fermentation apparatus originally developed to determine the biogas yield is absolutely suited to also assess the impact of different digester loads and retention times.

    Recommendations

    The problem of the suitability and the potential of different materials, the optimum reactor performance and the combination of different processes of energy generation from renewable but also conventional resources will increaseingly become the focus of laboratory tests. The following subjects have to be taken into account:
  • - Testing different materials on their suitability
  • - Evaluation security of common and new co-ferments
  • - Guidelines for mixtures to optimize reactor performance
  • - Mixtures of different substrates and co-ferments available to a particular operator (also with the help of simulation models)
  • - Processing changing quantity proportions of plants won from a rotation of crops altered for energy generation
  • - Other parameters like pre-fermentation, particle size and fer mentation supplements.
  • Perspective

    These tests with a high practical relevance are supposed to contribute to a reliable method of producing biogas, in order to optimize the yield of gas production, but also to find a calibration of less costly procedures like those involving Near Infrared Spectroscopy (NIRS).  相似文献   

    20.
    Through their use of energy and materials, universities cause a great deal of environmental pollution which could be reduced considerably by an effective choice of organizational and technical measures. There are some examples for environmental protection measures at several universities, but a professional environmental management system (EMS) for universities with a systematic approach to reduce the consumption of resources is lacking. At the University of Osnabrück, the basis for an EMS applicable for a university has been developed for the first time in Germany and the use of this system can also be transferred to other universities. The EMS is composed of ten building blocks, for example, alteration of the administration’s organizational structure, adoption of environmental guidelines, analysis of the energy and material flows which result in an eco-balance, an environmental program or measures to inform the staff and to help to involve them in environmental management. Over the next months, these ten building blocks will gradually be implemented at the University of Osnabrück. Five articles will provide an overview about the EMS developed for the University of Osnabrück as a whole and will describe parts of the material and energy flow analysis, and the planned environmental information system.
  • Part I: An Environmental Management Model for Universities: From Environmental Guidelines to the Involvement of Employees
  • Part II: The Energy Balance of the University of Osnabrück: Analysis of the Energy Flows and Conclusions
  • Part III: The Traffic Balance of the University of Osnabrück: Calculation of the Environmental Pollution which is caused by the University’s Commuters and Business Trips
  • Part IV: A Concept of Waste Reduction for the University of Osnabrück: Constructing the Waste Balance and Measures to Inform and Involve the Staff
  • Part V: The Planned Environmental Information System of the University of Osnabrück: Concept and Integration into the Management Information System
  •   相似文献   

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