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1.
为研究紫外吸收剂2-羟基-4-甲氧基二苯甲酮-5-磺酸(BP-4)的最大生物降解能力,采用欧洲经济合作与发展组织(OECD)生物降解测试标准方法——303A模拟试验-污水好氧处理:活性污泥单元法,建立并进行了城市污水处理厂曝气池环境模拟试验。研究结果表明:在单一新鲜活性污泥作为接种物条件下,BP-4在第47天达到降解稳定期,溶解性有机碳(DOC)去除率平均值为36.90%±5.68%(n=18)。在以10种不同来源混合接种物条件下,BP-4在第41天达到降解稳定期,去除率平均值为33.11%±4.87%(n=17)。研究结果表明BP-4在环境中的降解能力有限,在本模拟方法试验条件下只能部分降解。  相似文献   

2.
The activity of microorganisms in the activated sludge can be measured with a bio-activity sensor. The signal of the sensor reacts sensitively to changes in substrate concentrations and the appearance of toxic materials. With the sensor, it is possible to check biological wastewater treatment plants online with regard to their microbial activity and to supervise the flowing sewage with reference to its toxic potential.  相似文献   

3.
Results of the study In a long-term perspective innovations which are directed towards the principles of sustainable active pharmaceutical ingredients (APIs) will result in substituting problematic substances with other ones which are therapeutically effective as well as degradable in an environmentally compatible way. The substitution leads to a considerable decrease in water pollution with respect to the influx of APIs. The article summarizes the standard of knowledge considering measures with which such innovations and the consequent water improvement can be achieved. Discussion With an adequate promotion of research within this field and a modified scientific education the appliance of specific molecular designs could be established in the pharmaceutical sciences and industry. Examples will show that this, as a first step, may result in effective structures (model structures, which are already comprising synthetic substances) being modified so as to achieve a good degradability. By providing a list with evaluated and successfully established practical examples the basic practicability of this approach can convincingly be demonstrated. Especially within a changed political framework it will on this basis be possible as a second step to show that the approach also works in a systematic way when it comes to a broader development of new substances. With the help of advertising efforts the swift establishment of those innovations within the pharmaceutical market can be achieved thus supporting an accelerated environmental relief. Conclusions There is an option to develop a method of resolution, which will bring forward a trans-formation within the pharmaceutical industry with respect to a sustainable development. Those new methods furthering an improved degradability of pharmaceutical substances will result in an important reduction of influx into the environment and they will at the same time be able to improve the pharmaceutically relevant properties. Recommendations and perspectives The hereby suggested strategic approach is also applicable for environmentally relevant chemicals, i.?e. not for pharmaceuticals only.  相似文献   

4.
Humic substances are an important component of organic carbon in natural waters. Their character and properties are determined by the sources and the processes of their origin. Humic substances are not exclusively refractory compounds, but they are involved in several transformation processes in the water. It is not possible to directly analyze humic substances, therefore several methods were applied for their characterization. The presented LC-OCD-technique is a size-exclusion-chromatography with online UV- and carbon detection. Carbon fractions, e.?g. humic substances were differentiated by their molecular size. The portion of humic substances in sediment porewaters of the rivers Elbe, Rhine, Danube, Oder, Müritz-Elde-Waterway was determined. With only a few exceptions it ranges from 50 to 67?% of the dissolved organic carbon. The high molecular weight fraction accounts for 10 to 34?%, and the fraction of the low molecular weight substances was from 7 to 37?%. The ratio between the spectral absorption coefficient (254?nm) and the organic carbon is called SUVA (L/mg × m) and is an inidicator of the proportion of unsaturated bonds in the humic substances. Both high molecular herbal components (e.?g. cellulose, lignin) and biological degradiation products (e.?g. amino acids, sugar) are involved in sediment porewater transformation and degradiation processes. This demonstrates the distribution of the dissolved organic carbon between the fractions.  相似文献   

5.
6.
大量缺乏毒性信息的化学品最终进入环境水体,对人类及生态生物产生潜在的危害与风险。提高化学品生物毒性测试与评估技术的通量和效率,是实现毒害化学物质环境与生态健康风险防控的关键。作为一种可以实现高通量测试的脊椎动物模型,斑马鱼胚胎测试在化学品的毒性评估中应用广泛。随着组学技术的发展,毒理基因组学可有效提取毒害化学品致毒过程中干扰生物学通路的信息。这些机制信息可用于对单物质或复合污染物生物毒性的筛选和预测。本文综述了不同斑马鱼胚胎测试技术在化学品毒性筛选评估管理与水环境复合污染毒性监测中的发展和应用,详细介绍了一种新型斑马鱼胚胎简化转录组学技术的方法流程和优势,并探讨了综合斑马鱼胚胎毒性测试、行为分析和组学等不同测试技术在化学品毒性测试、环境监测与评价中的应用前景。  相似文献   

7.
Chromium, especially the metal and its trivalent and hexavalent compounds, are of great industrial interest. As a matter of fact, chromium workers have an occupational risk. While trivalent chromium compounds are of low toxicity, the hexavalent compounds are strong oxidants which cause not only a direct tissue damage (=acute toxicity), but also possess a carcinogenic, mutagenic and teratogenic potential (=chronic toxicity). Since the kidney is the main target organ after oral and/or dermal uptake of hexavalent chromium is the kidney, tubular necrosis might be the result of an acute toxification. This report presents anin vitro assay with cultured renal epithelial cells which allows the evaluation of the acute toxicity not only of trivalent and hexavalent chromium compounds, but also of various hazardous substances used in industrial production process. As shown here, an acute toxic effect was not detectable for the trivalent chromium (chromium (III)-chloridehexahydrate) within 24 h of exposure to concentrations as high as 200 μmol/l. In contrast, renal epithelial cells which were exposed to hexavalent chromium (potassium chromate) for the same time period exhibited marked signs of toxicity such as a rounding and detachment of the cells from the floor of the culture plates, an elongation and perinuclear development of vacuoles in the vital cells which were still attached, as well as a cells swelling and cellular fragments caused as a result of necrotic cell death and subsequent lysis. This toxic effect was already observed at concentrations above 5 μmol/l. In conclusion, thein vitro assay might be a good tool for the screening of hazardous substances in industrial medicine. More-over, by using additional tests, the chronic toxicity of such substances can also be examined. The selection of specific cell strains such as hepatocytes, neural cells etc. also allows the evaluation of toxic effects in individual organs. Thein vitro assay can not only be applied for the investigation of basic mechanisms of toxification and detoxification of specific compounds, but also delivers a basis for the screening of the reactivity of individual hazardous substances. Finally, the assay would allow a reduction in animal experiments as well as the simultaneous testing of a reactivity to multiple, hazardous substances.  相似文献   

8.
Over the last years, the obviously increasing, hormone-dependent impairments observed in humans and animals, as well as the increased occurrence of hormone-dependent types of cancer, are sometimes associated with environmental chemicals which are suspected to imitate or block the effects of natural hormones. For a variety of environmental chemicals an endocrine efficacy could already be demonstrated. Little is known, however, about a possible hormonal activity of plant protection agents which are at present certificated in the Federal Republic of Germany. The aim of the present study was the in vitro testing of at least 57 active ingredients of pesticides and growth regulators certificated in the Federal Republic of Germany, for their possible estrogenic activity. The E-Screen-Assay based on the human breast cancer cell line MCF-7 was used as the suitable test system. For at least 8 of the tested substances, an receptor-mediated estrogenic activity could be shown in vitro. With the exception of one substance, 7 active ingredients displayed a very weak affinity for the human estrogen receptor. Their ability to displace 17β-estradiol from the receptor was low. Only the herbicide Pendimethalin is to be classified as a full estrogen receptor agonist; it is able to displace 17β-estradiol almost completely from the receptor. Howeverm the estrogenic potency of Pendimethalin, in comparison to 17β-estradiol, was seen to be as small as the estrogenic potency of the other 7 substances tested positively in the E-Screen-Assay. Among this 7 substances, two could not be classified as estrogenically active anymore, because their affinity to the human estrogen receptor was too weak. The relevance of the available results for livng organisms should be clarified in further in vivo investigations.  相似文献   

9.
悬浮填料生物膜工艺的研究进展   总被引:16,自引:0,他引:16  
悬浮填料生物膜工艺又称为移动床生物膜反应器工艺,是上世纪90年代初迅猛发展起来的一种新型水处理工艺.它既可以作为独立的生物处理系统,也能够与活性污泥法组合以增加后者的处理效能,还可以作为中高浓度工业废水的生物预处理手段.本文总结了悬浮填料生物膜工艺的流体力学、生化动力学规律、悬浮填料的开发现状,探讨了此工艺在市政生活污水、工业废水、低污染物浓度的水处理领域的研究和应用进展.进一步开发高效、廉价的功能型悬浮填料,提高填料的有效比表面积,优化与确定工艺和运行参数,将推动悬浮填料生物膜工艺在我国的全面应用.图3表1参64  相似文献   

10.
全氟烷基羧酸(perfluorocarboxylic acids,PFCAs)普遍具有环境持久性、生物富集性及生物毒性效应.随着政府和国际组织对PFCAs生产和排放的监控和管制,探究PFCAs的间接来源变得愈加迫切.氟调醇(fluorotelomer alcohols,FTOHs)是生产含氟聚合物和含氟表面活性剂的重要...  相似文献   

11.

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   

    12.
    化学品的大量使用和排放进入水环境,对水生态系统产生诸多不利影响。因此,流域环境管理的重点之一就是如何筛查具有潜在风险的优先污染物。对于流域环境介质中污染物筛查而言,难点和关键是如何建立高效的分析方法来尽可能多的获取环境介质中的污染物信息,进而对其危害及风险水平进行判断与筛查。对在流域环境介质中污染物筛查方面具有潜在应用可能性的环境分析方法进行了综述,提出了以高通量分析方法为基础的基于概率风险分析的流域优先有机污染物筛查方法体系,并对体系中涉及的筛查基准、数据选择等关键问题进行了讨论。  相似文献   

    13.
    Results The available research results concerning the application of innovative methods of wastewater and drinking water purification to eliminate pharmaceuticals are summarized in the present paper. An increase of the activated sludge (aerobic sludge) age to 8–10 days in treatment plants can improve the metabolization of less persistent pharmaceutical agents whereas expansion of the sojourn time beyond 10 days will not result in a remarked increase of degradation for most pharmaceutical substances. First results have shown that wastewater treatment plants with integrated membrane bioreactors (MBR) using micro- and ultrafiltration membranes do not provide significantly better results compared to the conventional wastewater treatment plants with respect to the removal of organic micropollutants (including pharmaceutical residues). The use of powdered carbon in biologically treated wastewater is able to reduce pharmaceutical residues up to 80?% in the run-off water. Pilot studies scrutinize the treatment of highly contaminated effluents via catalytic photooxidation. Regarding the suitability of the method to reduce the contamination of drinking and wastewater with pharmaceuticals yet only few data from laboratory scale testing are available. Activated carbon filtration is preferably used for drinking water treatment. Primarily against the background of disinfection, ozonation is widely used for drinking water treatment, but for wastewater treatment the method is still at the experimental stage and will hardly become of practical importance because of high costs. Sustainable wastewater separation is grounded on decentralized concepts by considering material cycles (recycling) at the place of origin. In the long term, separation measures can significantly contribute to declining drug concentrations in drinking water. Regarding the quarrying of drinking water by bank filtration water, river water or artificially enriched ground water, end-of-pipe techniques are vital. Most commonly, activated carbon or activated carbon combined with ozonization is applied and assures a high drinking water quality. Discussion The advantages and disadvantages of the different water treatment methods mainly concern the varying degrees of effectiveness with respect to the elimination of very persistent pharmaceutical agents, the generation of problematical metabolites and additional waste materials, hygienic problems, energy needs and the necessity to employ appropriate technical staff for operation. Although the biodegradation of very persistent drugs cannot be enhanced by an extension of the activated sludge age, this modification should be considered in sewage plants to reduce the contamination with less persistent medical agents. Compared with conventional wastewater treatment, membrane bioreactors provide the advantage of a better control of biological activities on the plant and a comparably small plant size but high investment and operation costs. Additionally, pharmaceuticals such as carbamazepin are only insufficiently removed from wastewater by membrane bioreactors. The regular use of powdered activated carbon in sewage treatment plants would also increase the costs of wastewater treatment and would additionally exclude the further use of sewage sludge in agriculture. Currently, in Germany the further use of sewage sludge is handled differently by the Federal States and discussed controversially. The implementation of ozonation as an additional treatment method in wastewater treatment plants is not realistic because of cost concerns. Additionally, the method produces analytically as yet not assessed metabolites with unknown (eco-)toxicological impacts. For this reason ozonation should currently not be applied unless the reaction products are removed subsequently by filtration through activated carbon. For industrial sewage photooxidation is in a state of testing but an application for municipal wastewater is, up to now, out of question. When river bank filtration is used for the supply of drinking water the use of activated carbon for purification should be essential. The lifetime of the filters is often defined by the filter capacities to eliminate radiocontrast media (e.?g., iopamidole, amidotrizoic acid). Many water supply companies already apply the ozonization prior to activated carbon filtration which supports the elimination of pharmaceuticals from the sewage. The unique developmental potential of the wastewater separation can be seen in the possibility to link up these methods with sustainable exploitation techniques and concepts (re-use of sanitized water, production of fertilizer, compost and biogas). Wastewater separation will not make ‘middle/end-of-pipe’ techniques dispensable but will make their handling more effective because concentrations of pharmaceutical agents are higher in separated effluents compared to those usually found in municipal wastewater, which in mixing sewage systems is even diluted by surface runoff. Conclusions Following today’s state of knowledge activated carbon filtration (eventually coupled with ozonization) is best suited to remove drug residues and other xenobiotics from raw water. Water works that do not apply the activated carbon filtration technique for cleanup of bank filtration water should consider an upgrade. The ozonization is primarily required for disinfection of the water. As no acute health hazard proceeds from drinking water contamination by pharmaceuticals at the present time, the upgrade of wastewater treatment plants by one of the aforementioned innovative methods is currently not required in view of drinking water quality. This offers the opportunity to develop sustainable approaches that already aim to reduce drug contaminations of wastewater and hence of ground-, surface- and drinking water. Recommendations and perspectives On a short- to mid-term perspective enriched sewage of hospitals, nursing homes and other medical facilities should be collected and treated separately. From a technical point of view the conditioning of separated hospital effluents (yellow- and greywater) via activated carbon or membrane filtration is possible but should be combined with disinfection. On a mid- and long-term scale sustainable sanitary concepts based on wastewater separation (black-, grey- and/or rainwater) associated with the recycling of mineral nutrients (nitrogen, phosphorous and potassium) should be realized for development, industry and trade areas, buildings with public lavatories, airports, motorway service areas, and large office and hotel buildings. Strategies focusing primarily on up-grading of municipal wastewater treatment plants are currently existing but the related technologies are largely in a test phase. This is why a particular technique should not be favored at the moment. The combination of various techniques (i.?e., ozonization combined with activated carbon filtration) is known to be very efficient for the removal of pharmaceutical residues from water, but the combination cannot be expected to become of importance in treatment of domestic wastewater because of high costs. Moreover, improvement of wastewater treatment technologies to remove pharmaceutical residues will not make the employment of end-of-pipe techniques in water works redundant and therefore will not lead to saving of expenses.  相似文献   

    14.
    采用生态毒理学常用的大型溞(Daphnia magna)和活性污泥(activated sludge)作为试验系统,对制革废水处理系统各个环节出水进行毒性试验,以评价其处理效果。按照OECD标准试验方法,选取本实验室繁殖的大型溞(溞龄小于24 h),和采自以处理生活污水为主的污水处理厂活性污泥,分别使用重铬酸钾和3,5-二氯酚作为参比物验证大型溞和活性污泥的毒性敏感性。以大型溞活动抑制和活性污泥呼吸抑制作为毒性终点,利用48 h静态试验和3 h曝气试验分别评价水样对于大型溞活动和活性污泥呼吸作用的急性毒性效应。统计各试验组大型溞的活动情况和活性污泥的呼吸速率,分别将其与空白对照组进行比较,计算大型溞的活动抑制率和活性污泥的呼吸抑制率,采用Bliss法统计制革废水处理系统各个环节出水对大型溞和活性污泥的半数抑制浓度(EC50)。结果表明:制革废水依次经过厌氧脱硫反应器、脱色厌氧反应器、微曝气反应器和厌氧氨氧化反应器的生物处理系统处理,其出水对大型溞和活性污泥的急性毒性已大为降低。进水、厌氧脱硫反应器出水、脱色厌氧反应器出水、微曝气反应器出水和厌氧氨氧化反应器出水对大型溞活动抑制试验的48 h-EC50分别为41.3%、32.2%、48.0%、91.2%和无抑制作用;活性污泥呼吸抑制试验3 h-EC50则分别为178.2%、101.5%、689.7%、184.6%和无抑制作用。总体上毒性呈现逐渐降低的趋势,而且大型溞比活性污泥更为灵敏。大型溞和活性污泥的生态毒性结果与化学分析的结果相互补充,可为制革废水处理提供预警和效果评价提供科学依据。  相似文献   

    15.
    种衣剂中使用的杀虫剂会影响鸟类对种子的消耗量,从而影响鸟类的实际暴露风险。虽然量化这种对消耗量的影响目前不被考虑在环境风险评估中,但这是一个潜在的选择,例如在比较不同农药的暴露风险时应予以考虑。这种方法可以突出用于防止鸟类服用致死或亚致死剂量的杀虫剂。为了制定一个标准,我们在已建立的笔试方法的基础上开发了一个室内测试程序,包括饥饿期的“两选择”和“无选择”阶段。测试期间采用动物福利的最高标准。利用统计方法确定最合适的重复次数并分析最终结果。杀虫剂对种子消耗量的影响用处理后种子与未处理种子消耗的比率表示。该消耗因子可作为种子处理的鸟类风险评估中的回避因子。 作为案例,我们提出了一个获得绿雀(Carduelis chloris)和日本鹌鹑(Coturnix japonica)对未处理和使用杀真菌剂处理的油菜籽(Brassica napus)的种子和特定物种消耗量因子的试验程序。总体来说,两种鸟类的体质都没有受到试验程序的负面影响。试验程序适用于显示预期消耗模式的差异,例如在“两选择”试验中比在“无选择”试验中对经过杀真菌剂处理的种子有更高的避免性。而种子消耗量在不同物种和杀真菌剂处理组有差别,这使得我们可以对不同杀真菌剂的规避效应进行排序。使用本文所提出的标准程序可以针对更多鸟类物种得到具有可比性的农药和物种特定的消费因子。  相似文献   

    16.
    Biocides are active substances and products which are intended to destroy (…) any harmful organism by chemical or biological means. Typical applications are for instance wood preservatives, antifouling products or disinfectants. In the European Union the use of biocidal products is regulated since 1998 by the Biocidal Product Directive 98/8/EG (BPD). The BPD was transposed into German law in 2001 by the “Biozid-Gesetz”. The Federal Environment Agency is responsible for the environmental risk assessment of biocidal active substances and products under the “Biozid-Gesetz” in Germany. The European Commission has to evaluate the BPD seven years after endorsement and if necessary, has to submit a proposal for the revision of the directive. It is expected that the European Commission will publish soon a review of the enforcement of the BPD together with suggestions for the revision of the directive. In this article the German Federal Environment Agency summarises suggestions for the revision of the BPD based on its ten years experience with the directive: The scope of the BPD needs an exact clarification of borderlines in order to avoid confusion with other legislation. Food and feeding stuff together with natural products like lavender branches and cedar wood, which are used as attracting or repellent agents, have to be excluded from the scope of the BPD. Special data requirements for natural oils and pheromones should be developed to take the complex composition of these substances into account. The advantages of a centralised and decentralised authorisation procedure are discussed for biocidal products in special product types. Furthermore we stipulate that biocidal active substances which are nano particles are treated as separate active substances with own identities. Due to animal welfare reasons it should be obligatory to share data from vertebrate animal studies as it is already mandatory under the REACH regulation. The import of articles treated with biocidal active substances into the European market should only be allowed, if the active substance is approved for their biocidal use within the EU. Finally we suggest to implement an obligation to report the market shares or consumption rates of biocidal active substances and products. Together with procedural simplifications and adaptation in the scope of the directive, changes of the data requirements will be the key issues during the revision of the BPD. Most important, these changes should not reduce but ideally increase the level of protection for human health and the environment.  相似文献   

    17.
    Dissolved amino acids (3H-phenylalanine, 3H-proline) were accumulated and incorporated into proteins and glycoproteins by sea anemones. On objects (glass rods, pipe cleaners or filter paper) which had touched labelled anemones, tritiated substances could be detected. The mucus of labelled anemones was analysed by disc-electrophoresis. Tritium activity was found in the bands (stained by amino black). Anemone fishes adapted to labelled anemones had 4 times more tritium activity on their surface than control fishes. Most radioactivity was found on those regions which made closest contact with the anemones. The mucus of anemone fishes adapted to labelled anemones was also analysed by disc-electrophoresis. The analysis revealed protein-containing fractions in which 3H-amino acids were incorporated. The pattern of tritium activity in disc-electropherograms from labelled anemones corresponds to that of fishes adapted to those anemones. Anemones produce specific substances which influence the discharge of their nematocytes. These substances have special functions in the normal behaviour of the anemones. The substances provide protection against self-nettling and prevent the discharge of nematocytes into nearby objects which the tentacles continuously contact. The production of these substances by anemones is completely separate from the association with anemone fishes. The fishes thus simply exploit a mechanism existing independently in the anemones. Therefore, it is possible to form, in an aquarium, unnatural associations between anemone fishes and anemone species which never live in association with fishes in their natural biotope. On the basis of previous information, as well as on these new data, it is possible to develop a model which explains the control of nematocyte discharge: Substances with inhibitory qualities (protecting substances) are produced by the anemones themselves, and de-sensitize the sensory inputs of the anemones (nematocytes and sensory cells). Sensitization takes place as soon as the anemones come into contact with “stimulating substances”. This happens if anemones are touched by food objects or by anemone fishes which have been previously isolated from anemones. The surfaces of these fishes are not impregnated with protecting substances. Adapted anemone fishes, neighbouring anemones of the same species and other “adapted” objects are coated with the inhibitory substances and thus do not induce nematocyte discharge.  相似文献   

    18.
    On 26 April this year the German Environmental Advisory Council (SRU) published a statement on ‘Pharmaceuticals in the environment’ and pointed considerable need for action to understand and to reduce the risks from diffuse pharmaceutical inputs in the environment. On the one hand, it is urgently necessary to improve the database for environmental risk assessments; on the other hand measures should already be taken to minimize harmful inputs. Fortunately, the new regulations for an application for an authorization to market new pharmaceuticals require an environmental risk assessment. However, there is a lack of information on possible impacts from long time admitted medicines which may be responsible for harmful active substances detectable in the environment. To remove this data deficit, a European programme for risk evaluation of old pharmaceuticals should be established. It is necessary for an adequate risk assessment to look at all impacts of one active substance or all substances same-directed in their active potential summativ and to generate regularly consumption data in particular for the use of veterinary products. The hot spots of contamination are the introduction of large scale volumes of active pharmaceutical ingredients for human use like diclofenac and carbamazepin as well as hormones into surface waters, as well as the application of antibiotics-loaded economic fertilizers on soils. Not to be neglected is the application of antiparasitics in animals kept on pasture. With the assessment of the use of pharmaceuticals for all purposes special attention is needed on antibiotic resistance. For the mitigation of environmental exposures there are exposures measures necessary to reduce use of antibiotics in farming, for the application of new effective technologies in treatment sewage — as for example ozonation, filtration with activated carbon or membrane filtration — as well as for the labelling of environmentally harmful medicinal products.  相似文献   

    19.
    This paper describes a procedure for evaluating the desertification risk in threatened areas. The procedure is based on an eight-equation dynamic model of a generic human–resource system that can be applied to different desertification syndromes. For each application, interest focuses on finding all the possible long-term final states of the system and on defining the conditions that mark out sustainability and long-term desertification by means of unambiguous specific parameter relations. The procedure is applied to three typified cases in Spain: (A) rainfed crops in areas with high soil erosion risk; (B) irrigated intensive agricultural systems; and (C) commercial rangelands. Results show that, in case A, high profit scenarios are responsible for the final extension of desertification but do not determine the specific threshold between sustainability and desertification. They do, however, in cases B and C.  相似文献   

    20.
    This paper analyses the effect of variations in the elimination rates of four elimination models. Three types of variations are studied: (1) a periodic change between two elimination rates; (2) changes between two elimination rates at random times; and (3), an elimination rate varying smoothly in time, generated by having the elimination rate vary exponentially with temperature and a sinusoidally varying temperature. The elimination process is described by four different models: (1) a single compartment; (2) two compartments in parallel; (3) two compartments in series; and (4) the Goldstein-Elwood model. It is shown that for all 12 cases, the solutions can be given the same form as with constant elimination rates through reinterpretation of the parameters. As a special case, the use of elimination methods to estimate respiration is discussed and a possible source of error is pointed out.  相似文献   

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