Date de mutation:14/06/2019 - A Akademie der Naturwissenschaften Schweiz (SCNAT) Biodiversitätsforum Schweiz; Präsident Florian Altermatt Schweizerische Zoologische
Waste Design, Source Control und On-Site-Technologien: Der Weg zu einer nachhaltigen Siedlungswasserwirtschaft
A comprehensive analysis of the problems in today's wastewater
management identifies deficits in the handling of micropollutants,
the management of nutrients as well as management
strategies in general. Based on waste design,
source control and on-site technologies a possible path out
of today's technological lock-in situation is designed. The advantages
of waste design are discussed based on urine separation:
Wastewater composition is optimized in view of
wastewater treatment and the technology offers a variety of
possibilities for long term transition scenarios. In addition
the integration of on-site technologies into household appliances
is identified as a possible future development, which may help to improve the efficiency of wastewater handling
and may provide new management strategies.
Influence of the surface topography of stainless steel on bacterial adhesion
Bacterial adhesion on stainless steel may cause problems such as microbially induced corrosion or represent a chronic source of microbial contamination. The investigation focussed on how the extent and patterns of four bacterial species comprising three different phyla and a broad variety of physicochemical characteristics was influenced by the surface topography of AISI 304 stainless steel. Five types of surface finish corresponding to roughness values <I>R</I><sub>a</sub> between 0.03 and 0.89 μm were produced. Adhesion of all four bacteria was minimal at <I>R</I><sub>a</sub> = 0.16 μm, whereas smoother and rougher surfaces gave rise to more adhesion. This surface exhibited parallel scratches of 0.7 μm, in which a high proportion of bacteria of three of the strains aligned. Reduced overall adhesion was attributed to unfavorable interactions between this surface and bacteria oriented other than parallel to the scratches. Interaction energy calculations and considerations of micro-geometry confirmed this mechanism. Rougher surfaces exhibiting wider scratches allowed a higher fraction of bacteria to adhere in other orientations, whereas the orientation of cells adhered to the smoothest surface was completely random.
Urinseparierung - eine Alternative für die schweizerische Siedlungswasserwirtschaft?
Urine source separation in NoMix toilets with subsequent processing of urine offers the possibility to improve water pollution control and to recycle nutrients. Urine contains most of the nutrients ending up in wastewater and many micropollutants from the human metabolism. In most cases, efficient urine source separation would render nutrient removal at wastewater treatment plants obsolete. To obtain more stringent threshold values for phosphorus, merely a small technical effort would be necessary. The interdisciplinary research project NOVAQUATIS investigates the technical feasibility, social acceptance and possibilities of introducing urine source separation in Switzerland.
Fractal analysis of wood combustion aggregates by contact mode atomic force microscopy
Atomic force microscopy (AFM) is a powerful tool for the characterization of nanoparticles allowing to obtain fundamental parameters of morphology such as the size of individual particles, the number of particles per aggregate, the size distribution and finally the AFM allows one to determine the volume. All these parameters are accessible for the native aspect of the particles while AFM works under ambient temperature and pressure. We present here the analysis of wood combustion particles and their morphological parameters. Using our results for the 3D values, we were able to calculate the fractal dimension (Df) of the aggregates. As the Df is characteristic to the aggregation regime that particles undergo, we determined that wood particle aggregates follow a diffusion limited aggregation regime (Df=1.95). In parallel, in-situ analysis of the hydration effect has been studied in water at pH 7 and shows that the morphology is significantly influenced by the hydration. The composition observed by analytical electron microscopy (AEM) and atomic emission spectrometry (AES) enabled us to correlate the in-situ measurements by AFM with the hydration behavior of these particles and the fractal dimension.
Analytical electron microscopy as a tool for accessing colloid formation process in natural waters
Analytical electron microscopy was used to characterize aquatic iron-rich colloids. We focused our attention on a redox transition medium in the drainage water of a peat soil. In the anoxic peat water, observations by transmission electron microscopy and associated energy dispersive analyses (TEM-EDS) highlight the presence of spherical entities (~100-600 nm), containing only traces of iron. The increase of dissolved oxygen concentration favours the formation of iron oxy(hydr)oxides. In the oxygenated drain, particles with the same morphology and size range are present. Statistical TEM-EDS analyses show that they represent the only colloidal form of iron in the drain samples. Nevertheless, although Fe-K peaks appear clearly on EDS spectra, the proportion of iron in these colloids reaches at most 4% at. (whereas C + O > 90% at.). Structural information completes this study. Both electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) reveal the disparity between element distributions within the drain entities. Iron and calcium are preferably distributed on the outer sphere of the particle, whereas carbon and oxygen follow the theoretical variation of the signal intensity within a plain sphere. The implication of organic matter as nucleation site for iron precipitation is spectacularly demonstrated by the presence of nanometre-sized iron-rich phases highlighted by EELS line scans.
Was one sunspot cycle in the 18th century really lost?
The unusually long 4th solar cycle has recently been proposed by Usoskin et al. (2001) to be composed of two cycles. They argue that a weak and short cycle might have been lost in sparse sunspot data at the end of the 18th century. Here we check this hypothesis in different ways. First, we consider the sunspot number record in greater detail and compare in a statistical sense the sunspot observations of the period in question with those at other times. In a statistical sense the sunspot numbers recorded at the time of the proposed new cycle minimum are extremely untypical for other minima in the solar cycle record, but quite usual for the declining phase of the solar cycle. We also analyse other available proxies of solar activity, such as variations of the cosmogenic nuclides <SUP>10</SUP>Be and <SUP>14</SUP>C as well as auroral activity. These historical records are sufficiently long and provide an independent testimony of the cyclic behaviour of solar activity at the end of the 18th century. We found no evidence for a lost cycle in any of these data sets. Finally, we compare the proposed new cycle with the other cycles in the sunspot record. This reveals that the proposed "missing" cycle has very unusual properties, much more so than the original, standard cycle 4. Taken together, the evidence from these various tests strongly suggests that no cycle was missed and that the official sunspot cycle numbering and parameters are correct.
Participative and stakeholder-based policy design, evaluation and modeling processes
The general shift towards a polycentric understanding of policy making requires the involvement of stakeholders as active participants into the policy process at different levels of societal organization. This is particularly true for water resource management where the traditional approach to solving environmental problems with technological fixes and end-of-pipe solutions has started to shift towards a more thoughtful attitude. This involves the development of integrated approaches to problem solving and to include stakeholder perspectives. This tendency receives strong support by the European Water Framework Directive (WFD) that emphasizes an integrated approach to water resources management at basin scale. The WFD requires the inclusion of stakeholders in the process of developing and adopting a river basin management plan. In order to improve stakeholder-based policy design and modeling processes innovation and research is required in linking analytical methods and participatory approaches. Factual knowledge and analytical techniques have to be combined with local knowledge and subjective perceptions of the various stakeholder groups.
Forecasting year-class strength and yield of Lake Hallwil whitefish in an eutrophic lake
Forecasting potential yield may be important for adequately managing intensive commercial fisheries in highly productive lakes. Between 1986 and 1995, a small midwater trawl was used in November/December at night to assess population density and age structure of Lake Hallwil whitefish (<I>Coregonus suidteri</I>) in eutrophic Lake Hallwil, Switzerland. Acoustic data were recorded on the same day and night using dual beam technology. Year-class strength was calculated by virtual population analysis, based on catch statistics and age data of the commercial catch. Year-class strength varied highly between years. The number of young-of-the-year Lake Hallwil whitefish caught by standardized one-night trawling effort showed close correlation with year-class strength. Acoustic data corresponded well with pelagic fish abundance but not so well with size frequency distribution and biomass. Potential Lake Hallwil whitefish yield in subsequent years can be inferred from year-class strength assessed by the two methods, and using data on growth and size-at-harvest. Altogether, midwater trawling, combined with acoustics, was found to be an effective tool for forecasting year-class strength and yield of coregonids in small to middle-sized eutrophic lakes.
Sturgeons are more than caviar: a plea for the revival of sturgeons in the Danube river (extended abstract)
This paper compiles an extensive literature study (REINARTZ 2002)
on the biology, ecology and status of the Danubian sturgeon species. Only four out
of six acipenserid species, that were native of the Danube River Basin, reproduce
in the Lower Danube. In the Upper and Middle Danube, migratory sturgeons have
become extinct. Survival of the only true potamodromous sturgeon species: in the
Danube, the sterlet (<I>A. ruthenus</I>), depends solely on stocking in the Upper Danube.
Overexploitation and habitat degradation are the major threats . for Danubian
sturgeons. Hence, the enforcement and implementation of strict fishing regulations,
stocking programmes and river restoration are recommended as the most effective
management strategies. Telemetry and molecular genetics may help to elucidate
the natural behaviour and range of sturgeon habitats. Scientific research must be
the foundation of sustainable sturgeon management.