Erosional behaviour of sedimentary system mediated by bacterial EPS

What is it about?

Bio-sediments exhibit more complex characteristics than abiotic systems, and lead to different modelling methods compared to those in traditional settings. For instance, the thresholds for sediment initiation and subsequent erosion rates are no longer solely related to particle properties (e.g., particle size, the most widely used), but mediated by glue-like extracellular polymeric substances (EPS) secreted by microbes. From this point of view, it is easy to understand why sediments in field observations behave differently from predictions, usually appearing considerably strengthened. Our results indicate that the EPS mediation in sediment stability may vary with the rhythms of microbial growth, and re-profile the sediment stability during different stages of cementing processes. A conceptual framework for sediment erosion is hence put forward to transform traditional sediment system to EPS-sediment system.

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Why is it important?

Sedimentology and geomorphology have traditionally been seen as fields in which physical and chemical processes dominate. However, microbial communities should never be bystanders, because they suffuse all sedimentary environments on earth. Under hydrodynamic forces, they take part in an impressive range of sediment processes and thus exercising a formative influence on coastal evolutions. EPS-sediment systems are commonly observed on tidal flats while their working mechanisms on sediment erosion have not been fully understood. We believe that this contribution will benefit the biogeomorphological community.

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