Natürliche Oberflächenfilme im Seegebiet vor Sylt

The physical and chemical properties of the sea surface can be altered considerably by the formation of slicks and the accumulation of particles (including plankton). Investigations of natural slicks near the island of Sylt consisted of analyses of the dissolved and particulate surface-active substances, as well as the identification of plankton and bacteria collected by a surface-film sampler. The analyzed surface material consisted primarily of phytoplankton (Prorocentrum micans in particular), bacteria, detritus and dissolved compounds of fatty acids. These fatty acid compounds alone would not account for the slick. The slick appeared to be caused by the calm weather, the active accumulation of P. micans at the surface, and the increase in bacteria associated with this accumulation. Here a decrease was observed in the dissolved surface-active substances compared with the concentration usually found in normal surface waters, of which the total fatty acid content in a sample was taken as indicator. In some cases a correlation was found between fatty acids and particulate matter in naturally occurring slicks. Particularly large variations were found in the fatty acid patterns in the filtrate and filter residue at a time when no slick was present and no particulate matter had accumulated at the surface.

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Diese Arbeit wurde von der Deutschen Forschungsgemeinschaft im Rahmen des SFB 94, Hamburg, unterstützt.     

The role of safety research in road safety management

Mobility is a matter of great importance in daily life: However, it also causes costs and involves accident risks. To make mobility safer and reduce accident risks, a scientifically based road safety management is needed. Within such a safety management system, a concert of adequate and efficient strategies, tools and measures is developed and implemented. To ensure that the chosen means are efficient they should be derived from research evidence. Secondly, research is also needed to regularly monitor the impact of road safety management tools, serving as a “controlling instrument” for the appropriateness of safety management efforts. This article explains the main strategic aspects of safety management in Germany and illustrates it exemplarily on the basis of two recently implemented road safety measures.     

GIS-basierte Modellierung von Gewässerimmissionen

Goal and Scope

Environmental assessment of aquatic micro pollutants should consider the spatial and temporal variability of emission, transport and transformation. Simulation models coupled with Geographic Information Systems (GIS) provide digital maps of concentration patterns caused by the overlay of multipoint and diffuse emissions and natural attenuation processes in river basins. The paper gives an overview on GIS-based models for river basins and demonstrates the applicability by using some illustrating examples with GREAT-ER.

Main Features

Georeferenced models have several advantages: visualization of concentration patterns, investigation of spatial and temporal concentration profiles, analysis of exceedance of environmental quality standards, embedding in integrated river basin management systems.

Results and Discussion

GIS-based models allow a more realistic assessment. Monitoring programmes should be designed to deliver appropriate measured data for the evaluation and improvement of models.

Recommendation and Perspectives

The combination of digital maps, simulation models and environmental monitoring would provide better approaches for the risk assessment and water quality management of aquatic micro pollutants.     

Experimental study on the thermal oxidation of 2-chlorophenol in air over the temperature range 450-900 degrees C

The thermal oxidation of 2-chlorophenol (2-CP) in air was investigated using a perfectly stirred reactor at 1 atm over the temperature range 450–900 °C. The relative concentration of 2-CP was 1000 ppmV (equivalence ratio Φ = 0.03). About fifty organic products were identified as trace species. The concentration profiles of 2-CP, carbon oxides as well as those of seventeen major organic intermediates and six non-to-lower chlorinated dioxins and furans were presented as a function of temperature for a residence time of 2 s. The most abundant intermediate products were carbon monoxide, 2 H-pyran-2-one, chlorobenzene, 4-cyclopenten-1,3-dione, phenol, benzofuran, 2-chlorohydroquinone and 2-indanone. These concentration profiles have revealed that temperatures of at least 900 °C were needed to completely oxidize 2-CP, CO and all other organic byproducts to carbon dioxide. Reaction pathways accounting for the formation of most observed products are proposed.     

Melanin pattern morphs do not differ in metabolic rate: implications for the evolutionary maintenance of a melanophore polymorphism in the green swordtail, <Emphasis Type="Italic">Xiphophorus helleri</Emphasis>

Variation in melanin patterns among individuals, populations, and species is common in fishes of the genus Xiphophorus. In the variable platyfish, Xiphophorus variatus, variation in metabolic rate is associated with melanin coloration and the color morphs appear to be physiological specialists adapted to particular environmental conditions. This study investigates whether a melanin polymorphism in the green swordtail, Xiphophorus helleri, is likewise associated with variation in metabolic rate. We measured metabolic rate as oxygen consumption rate of both adult male and juvenile X. helleri in static respirometers. The oxygen consumption rate does not differ significantly between the spotted and nonspotted morphs in either group, suggesting that-unlike in X. variatus-selection on metabolic rate is not involved in maintaining the polymorphism in X. helleri. We suggest that explanations need to be sought for the evolution of melanophore diversity in Xiphophorus that are pertinent to each melanin pattern polymorphism or groups of similar polymorphisms.     

Evaluating Visitor-Monitoring Techniques: A Comparison of Counting and Video Observation Data

Two visitor-monitoring methods, video monitoring and counts by human observers, were compared in order to identify and evaluate their respective advantages and disadvantages. The analysis considered user numbers, user type (walkers, dog walkers, bicyclists, and joggers) and group size of visitors. Remarkable differences were found between the two methods for user type and use levels. At low use levels, evaluations based on video monitoring resulted in fewer single bicyclists compared to counts by human observers, whereas at high use levels, human observers counted fewer walkers and bikers than video-interpreters. Based on this comparative analysis, we derive recommendations for more effective visitor-monitoring approaches. All data were collected during a visitor-monitoring project in the Danube Floodplains National Park in Austria between 1998 and 1999.     

Feeding of calanoid copepods in relation to Phaeocystis pouchetii blooms in the German Wadden Sea area off Sylt

Surface sediments from the Svartnes basin (195 m deep) in Balsfjorden, northern Norway (ca. 70°N), were partially characterized to assess the nature and origin of the organic material present and its potential nutritive value for sediment-ingesting animals. Seasonal analyses were carried out on material collected between May 1979 and August 1980 for total organic matter, organic C and N, acid-extractable amino acids and lipids extractable with chloroform:methanol. Little or no seasonal variation was seen in any of the parameters analysed. The mean apparent organic content was 9.3% of sediment dry weight, the organic C content was 2.38%, the organic N content was 0.26% and the C:N ratio was 9.1:1. Acid hydrolysis of sediment yielded 575 mg of amino acids and 41 mg of NH₃ per 100 g sediment dry weight, the composition of the amino acids being similar to that of nutritionally highquality animal or microbial protein. Glucoseamine was not detected in acid hydrolysates of sediment, consistent with the absence of chitin. Chloroform:methanol extraction yielded 133 mg of material per 100 g sediment dry weight, 62% of which was accounted for by saponifiable lipids (fatty acids) and non-saponifiable lipids present in approximately equal amounts. Fatty alcohols accounted for 30% of the non-saponifiable lipids and phytol accounted for 40% of the fatty alcohols. Small amounts of very long-chain fatty alcohols characteristic of terrestrial plants were present, but long-chain monounsaturated fatty alcohols characteristic of marine zooplankton were essentially absent. Very small quantities of long-chain ketones characteristic of marine coccolithophores were detected. The major fatty acids present in sediments were 16:0, 14:0, 16:1 (n-7) and 18:1 (n-9), and 11% of the total fatty acids were comprised of a mixture of odd-numbered straight-chain and branched-chain moieties characteristic of micro-organisms. The data point to small amounts of material characteristic of marine and terrestrial photosynthetic organisms being present in sediments at any given time, whereas material characteristic of marine zooplankton is not present. The presence of material characteristic of micro-organisms is consistent with conversion of sedimenting material into a pool of sediment micro-organisms. Although the biological availability to sediment-ingesting organisms of the esterified fatty acids and the acid-extractable amino acids in sediments remains to be assessed, the maximum amounts available are equivalent to approximately 60 mg of polar lipid and 575 mg of protein per 100 g sediment dry weight. These amounts are small in relation to the production rates in the photic zone of the fjord, implying that the bulk of the energy flow in Balsfjorden occurs in its relatively short pelagic food chains.