Al naz von roete (Tit. 115,1) : Visualisierung und Metapher in Wolframs Epik

Stephan Fuchs-Jolie zeigt (anhand ausgewählter Textstellen in Wolframs Erzählwerken), wie der Dichter zugleich mit den Grenzen und Möglichkeiten von Repräsentation 0optischer Wahrnehmung in der Sprache die Potenzen und Aporien bildhaften, metaphorischen Sprechens diskutiert

Dissolved Phosphorus Concentrations in Surface Runoff from Agricultural Land Based on Calcium–Acetate–Lactate Soluble Phosphorus Soil Contents

The input of phosphorus (P) into aquatic systems can result in eutrophication that might manifest in algal blooms and oxygen deficiency and, subsequently, in a poor ecological status. Substance emission modeling on a river basin scale can help to quantify phosphorus emissions into surface water bodies and to address mitigation measures. The prerequisite is that suitable input data are available. The purpose of this study is to develop a modeling approach that allows the prediction of realistic phosphorus concentrations in surface runoff. During large-scale artificial rain experiments at 23 agricultural sites, dissolved P concentrations in surface runoff and subsurface flow were measured. The characteristics of the experimental sites were investigated by taking and analyzing soil samples and requesting information on the management from the farmers. From the data collected, two linear models were derived. The first model allows the prediction of dissolved phosphorus concentration in surface runoff from PCAL$_{soil}$ content. Applying the second model, the obtained concentration in surface runoff can be transferred to a concentration in subsurface flow. The resulting approaches were derived from realistic field experiments and, for the first time, allow the direct prediction of dissolved phosphorus concentrations in surface runoff and, in a second step, also in subsurface flow from spatially distributed PCAL$_{soil}$ content data. Integrating these approaches into substance emission models can improve their accuracy and, subsequently, allows a better planning of measures for the reduction in phosphorus emissions into surface water bodies

Large-volume samplers for efficient composite sampling and particle characterization in sewer systems

The assessment of pollution from sewer discharges requires flexible and reliable sampling methods. The characteristics of the sampling system must be known to allow comparison with other studies. Large volume samplers (LVS) are increasingly used for monitoring in sewer systems and surface waters. This article provides a comprehensive description of this widely applicable sampling system, gives insight into its comparability to standard methods, and provides recommendations for researchers and practitioners involved in water quality monitoring and urban water management. Two methods for subsampling from LVS are presented, i.e., collection of homogenized or sedimented samples. Results from a sampling campaign at combined sewer overflows (CSOs) were used to investigate the comparability of both subsampling methods and conventional autosamplers (AS). Event mean concentrations (EMC) of total suspended solids (TSS) derived from homogenized LVS samples and AS pollutographs were comparable. TSS-EMC of homogenized and sedimented LVS samples were also comparable. However, differences were found for particle size distribution and organic matter content. Consequently, sedimented LVS samples, which contained solids masses in the range of 3–70 g, are recommended to be used for particle characterization. The differences between homogenized and sedimented LVS samples, e.g., the quality of homogenization and the stability of samples during sedimentation in LVS, should be further investigated. Based on LVS results, average TSS concentrations of 50–60 mg/L were found for CSOs from centralized treatment facilities in Bavaria. With a median share of 84%, particles <63 µm were the dominant fraction

Influence of Gravel as Protection Layer on the Filter Run Time

Abstract: Since the beginning of the usage of slow sand filter (SSF) as one of the water treat-ment technologies, studies on how to enhance the performance have been conducted to date. One of the limitations in the current knowledge is regarding the method to increase the filter run time. The addition of protection layer may extend the filter run time. This paper focuses on the influence of gravel as the protection layer to the filter run time and turbidity removal. Gravel was chosen as the material of protection layer because of its low-cost and availability. A system-atic investigation by comparing only one different factor within the filter, which was protection layer, was conducted under the laboratory scale. The experimentconsisted of two filter columns namely K1 and K2. Both filters were constructed using the same filter depth, type of sand, and grain size distribution. The protection layer was added to filter K1, but not to filter K2. The sol-ids penetration and the increase of filter head loss wasused to evaluate the filter run time. A sta-tistical analysis was also carried out to examine the difference on the turbidity removal from both filters. The findings showed that by adding the protection layer, the filter run time could be extended up to 70%. Regarding to the turbidityremoval, there was insignificant difference between two filters

Four Years of Sediment and Phosphorus Monitoring in the Kraichbach River Using Large-Volume Samplers

Various sampling strategies come into operation to monitor water quality in rivers. Most frequently, grab samples are taken, but they are not suitable for recording the highly dynamic transport of solids and solid-bound pollutants. Composite samples reduce the influence of input and transport dynamics and are better suited to determine the annual river loads. Large-volume samplers (LVSs) produce both a composite sample over a long period of time and an amount of solids which allows for further analyses. In the small sub-catchment area of the Kraichbach river in Baden-Wuerttemberg (Germany) two LVSs have been installed to sample the river flow. The concentration of solids and phosphorus in the supernatant water and the settled sediment in the sampler have been determined and mean concentrations have been derived. Annual river loads were calculated in combination with discharge data from the nearby gauging station. Two sampling strategies of the LVS were tested and compared. For the first strategy, the LVS was used to collect quasi-continuous composite samples throughout the year, whereas, with the second strategy, samples were taken specifically for different flow conditions (low, mean and high flow). This study compares the advantages and constraints of both strategies. Results indicate that the first strategy is better suited to determine annual river loads. Quasi-continuous large-volume composite sampling is recommended for further monitoring campaigns

Experimental investigation of additively manufactured high-temperature heat exchangers

This article examines various additively manufactured heat exchangers for high-temperature applications. The heat exchangers differ in terms of their internal fin structure as well as optimizations in terms of manufacturing quality. Starting from a reference fin type, optimizations with focus on low pressure drop and high heat transfer are performed. The heat exchangers are investigated experimentally, focusing on the laminar flow regime between 60<Re<600. By means of a presented evaluation algorithm, the Nusselt numbers for the different fin types and designs are determined. The investigations show that even the smallest manufacturing deviations result in up to 70–120% higher f-factors and up to 30% higher Nu numbers. Taking these manufacturing deviations into account in the design process leads to very good agreement with the numerically determined values and the influence of surface roughness is comparatively small. Furthermore, the influence of internal heat radiation is of minor importance for the heat exchangers considered here