02 Fakultät Bau- und Umweltingenieurwissenschaften

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/3

Browse

Author: search.filters.author.Gerbersdorf, Sabine UlrikeSubject: search.filters.subject.500

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Microbial biostabilization in fine sediments
    (2022) Gerbersdorf, Sabine Ulrike; Wieprecht, Silke (Prof. Dr.-Ing.)
    Microbial biostabilization has increasingly received attention over the last years due to its significance for the dynamics of fine sediments in fluvial and coastal systems with implications for ecology, economy and human-health. This habilitation thesis highlights the contributions of the applicant and her team to this multi-disciplinary research area and is based on eight core publications that are presented in seven chapters. First, the topic of biofilm and biostabilization is introduced and second, the materials and methods applied are presented before own research findings are discussed. To start with, the stabilization potential of heterotrophic bacterial assemblages has been emphasised as well as the adhesive properties of the protein moieties within the EPS (extracellular polymeric substances) that are more significant than previously thought. Furthermore, the engineering potential of estuarine prokaryotic and eukaryotic assemblages has been studied separately and combined to reveal the effective cooperation of mixed biofilm that resulted in highest substratum stabilization although the effects were not clearly synergistic (=more than additive). The significance of biostabilization could be evidenced as well for freshwaters where highest adhesive capacity and sediment stability occurred during spring. Microbial community composition differed accordingly to result in mechanically highly diverse biofilm. Moreover, the importance of two of the most influential abiotic conditions, light intensity and hydrodynamics, was shown for biofilm growth, species composition and functionality - here biostabilization. In order to test adhesive properties at the relevant mesoscale (mm-cm) but non-destructively and highly sensitive, MagPI (Magnetic Particle Induction) has been applied. The last chapter concerns technical aspects to further improve its performance while demonstrating the impact of material and geometry and the importance of both, magnetic field strength and field gradient for the physics of the MagPI approach.
  • Thumbnail Image
    ItemOpen Access
    Combining field and laboratory measurements to determine the erosion risk of cohesive sediments best
    (2015) Noack, Markus; Gerbersdorf, Sabine Ulrike; Hillebrand, Gudrun; Wieprecht, Silke
    In contrast to non-cohesive sediments, the incipient motion of cohesive sediments is characterized by much more complex interactions between several sedimentary, biological, and chemical parameters. Thus, site-specific investigations are required to obtain information about the erosion stability of cohesive materials. This becomes even more relevant for contaminated sediments, stored in riverine sediments as a “burden of the past”, because of their remobilization potential during flood events. This article represents a twofold measuring strategy for the detection of erosion thresholds: an in situ device for determination of critical shear stresses in the field, and a laboratory approach where sediment cores are withdrawn and subsequently analyzed over depth. The combined measuring strategy was applied in the River Elbe and at selected sites of the catchment of the River Saale. The results show a great variety of erosion thresholds over depth, demonstrating the need to conduct vertical analyses, especially when addressing buried layers with contaminations. The latter is only possible in the laboratory but the in situ device revealed clear benefits in capturing the loose flocculent layer on top of the sediment that might be easily lost during sediment retrieval and transport. Consequently, it is ideal to combine both approaches for a comprehensive insight into sediment stability.