Biophysical flocculation reduces variability of cohesive sediment settling velocity

Ye, L. and Penaloza-Giraldo, J. and Manning, A.J. and Holyoke, J. and Hsu, T. (2023) Biophysical flocculation reduces variability of cohesive sediment settling velocity. Communications Earth & Environment, 4.

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Official URL: https://doi.org/10.1038/s43247-023-00801-w

Abstract

Biophysical cohesion, introduced predominantly by Extracellular Polymeric Substances (EPS) during mineral flocculation in subaqueous environments, plays important role in morphodynamics, biogeochemical cycles and ecosystem processes. However, the mechanism of how EPS functioning with cohesive particles and affects settling behaviors remain poorly understood. We measure initial flocculation rate, floc size and settling velocity of mineral and artificial EPS (Xanthan gum) mixtures. Combining results from these and previous studies demonstrate coherent intensification of EPS-related flocculation compare with those of pure mineral and oil-mineral mixtures. Importantly, the presence of EPS fundamentally changes floc structure and reduces variability of settling velocity. Measured data shows that ratios of microfloc and macrofloc settling velocity for pure mineral flocs is 3.9 but greatly reduced to a lowest value of 1.6 due to biological EPS addition. The low variability of settling velocity due to EPS participation explains the seemingly inconsistent results previously observed between field and laboratory studies.

Item Type: Article
Additional Information: Open Access
Subjects: Maritime > General
Divisions: Maritime
Depositing User: Helen Stevenson
Date Deposited: 18 Jul 2023 15:05
Last Modified: 18 Jul 2023 15:05
URI: http://eprints.hrwallingford.com/id/eprint/1549

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