Wirkungsschwellen für chemische Stoffe in Biosystemen Eine theoretische Betrachtung

Die aus der chemischen Umsetzung mit endogenen Molekülen resultierende biologische Wirkung von Fremdstoffen wird diskutiert, ausgehend von den Grunds?tzen der Thermodynamik und Kinetik. Dabei führt ein unter vereinfachenden Annahmen durchgeführter Vergleich der thermischen Energieverteilung von Molekülen mit typischen biochemischen Aktivierungsenergien zu dem Ergebnis, da? aus statistischen Gründen für jede mit stofflichen Umsetzungen zusammenh?ngende biologische Wirkung ein Schwellenwert existieren sollte.     

Veränderung von Biokonzentration und Wirkung vom PSM in Anwesenheit von Huminstoffen

Humic substances, in aqueous bodies primarily fulvic acids, may demonstrate an inhibitory as well as an activating influence on organisms. We present evidence with bacteria-containing algal cultures and with cultures of the nematodeCaenorhabditis elegans. Structural elements of the fulvic acids which may be responsible for such effects are not yet known. Furthermore, the presence of fulvic acids may lead to increases in bioconcentration of xenobiotics. Increase in the toxicity of xenobiotics in the presence of humic substances have also been described. We present studies applying lethal as well as sublethal toxicity endpoints.     

全球化学品管理战略:机遇和风险

由以往和化学品安全相关的国际活动发展而来的国际化学品管理战略(SAICM)得到了联合国环境署(UNEP)理事会的支持.全球化学品行业认为SAICM应该被作为实现世界可持续发展首脑会议议定目标的路线图.全球在化学品安全使用问题上的不断进步将要求生产者、销售者、使用者、政府和其他利益相关方在生产链各有关环节责任分担的基础上采取共同协调的行动.从这个意义上说,制定一个全球战略提供了通过建立新的伙伴关系来实现化学品安全的机会.但是,如果SAICM成为国家、地区和国际层面附加的更严格的调控手段的基础,则其可能达不到期望的影响.     

Flow and diffusion measurements in natural porous media using magnetic resonance imaging

Flow and diffusion of water in natural porous media, quartz sand, and calcareous gravel were measured using a 1.5-T clinical magnetic resonance tomograph. The spatial resolution of the dynamic measurements was 1.32 x 1.32 x 5 mm3, and the time between two cross-sectional measurements was approximately 10 s. The measured coefficients of molecular diffusion for water were in good agreement with theoretical data. Flow was measured without any tracer at velocities between 0.15 and 6.67 mm/s. The results, based on a calibration within one part of the column, were in good agreement with data obtained from a tracer experiment and from a numerical model. It was possible to measure the flow velocity in larger pores and preferential flow paths directly. The results of the flow measurements in smaller pores reflected the mean velocity within that volume element. In that case the obtained values were close to the average linear velocity. Since the time resolution is high a monitoring of flow processes is possible. The pore space was imaged with a spatial resolution of 0.5 x 0.5 x 0.5 mm3. Here, the porosity of pores that are larger than 0.2 mm can be measured directly; for smaller pores a calibration is necessary.     

Linking socio-economic factors, environment and land cover in the German Highlands, 1945-1999

Land-cover changes are caused by human activities and natural ecological processes. Thus, our study uses an interdisciplinary approach to research land-cover changes. We present a method to (i) link socio-economic/environmental factors and land-cover changes, (ii) identify indicators of land-cover changes, and (iii) distinguish between socio-economic and environmental indicators associated with local types of overall land-cover changes. The study was conducted in the Lahn-Dill Highlands, Germany, a typical marginal rural landscape. In this region, we investigated land-cover changes occurring over the period 1945-1999. Land-cover data were derived from multi-temporal aerial photographs. Types of overall land-cover changes characterising the districts within the study area were differentiated. With the help of redundancy analysis (RDA), we analysed the relationships between land-cover changes and widely available socio-economic/environmental factors. The results reveal that both individual land-cover changes at patch level and types of overall land-cover changes characterising districts are correlated with socio-economic and environmental factors. Whereas the stable environmental factors are drivers of land-cover changes in our rural study area, socio-economic factors introduced into the analysis mostly result from land-cover changes. We identified correlative socio-economic indicators that cannot explain land-cover changes, but that in combination with the environmental factors can be used to greatly facilitate the reconstruction of past land-cover changes and thus lead to a better knowledge of land-cover history. Based on the types of overall land-cover changes, the results of the study can be adopted for the study of land-cover changes in other regions.     

Explosions in closed pipes containing baffles and 90 degree bends

There is a general lack of information on the effects of full-bore obstacles on combustion in the literature, these obstacles are prevalent in many applications and knowledge of their effects on phenomena including burning rate, flame acceleration and DDT is important for the correct placing of explosion safety devices such as flame arresters and venting devices. In this work methane, propane, ethylene and hydrogen–air explosions were investigated in an 18 m long DN150 closed pipe with a 90 degree bend and various baffle obstacles placed at a short distance from the ignition source. After carrying out multiple experiments with the same configuration it was found that a relatively large variance existed in the measured flame speeds and overpressures, this was attributed to a stochastic element in how flames evolved and also how they caused and interacted with turbulence to produce flame acceleration. This led to several experiments being carried out for one configuration in order to obtain a meaningful average. It was shown that a 90 degree bend in a long tube had the ability to enhance flame speeds and overpressures, and shorten the run-up distance to DDT to a varying degree for a number of gases. In terms of the qualitative effects on these parameters they were comparable to baffle type obstacles with a blockage ratios of between 10 and 20%.     

Teil II: Verfahren zur Monetarisierung von Ökosystemleistungen

As it is practically impossible in an industrial society to reduce impacts into ecosystems to a level that would preclude any damages, the need for damage valuation arises. One of the available valuation tools is the economic approach. Subsequent publications present this approach using the example of soils. In this second part, two methods are presented for monetarising ecosystem services, the contingent valuation method, the valuation on the basis of restoration and replacement costs. Common arguments against the monetarisation of ecosystems, like the omission of intrinsic values or the incomplete information of individuals, are then discussed. In conclusion, limits and possibilities of monetarising ecosystem services are described.     

Determination of chemical warfare agents

Ethylarsine dichloride was used during WW I as a chemical warfare agent. Residues of this chemical warfare agent and its metabolites are still present today and continue to contaminate soil and water. A gas Chromatographic method for the detection and determination of ethylarsine dichloride is shown. Six dithiols were tested as possible derivatization reagents for ethylarsine dichloride. With selection of the dithiol, matrix interferences can be eliminated because of the different retention times of the derivatives.