Flocculation and de-flocculation of suspended matter in estuaries

Eisma, D.

doi:10.1016/0077-7579(86)90041-4

Cited by 442 publications

(272 citation statements)

References 38 publications

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“…This effect has been observed in the field in in situ studies of flocs over a tidal cycle (Kranck and Milligan, 1992) and in relationship to regions of different turbulence within an estuary (Eisma, 1986, Luettich , Jr. et al, 1993). In laboratory studies, aggregates have been formed using many different types of floccdators ranging from shaken bottles (Kranck, 1986) through simple annuiar flumes (e.g.…”

Section: Prevr'ous Workmentioning

confidence: 69%

A laboratory assessment of the relative importance of turbulence, particle composition, and concentration in limiting maximal floc size and settling behaviour

Milligan

Hill

1998

Journal of Sea Research

113

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Section: Prevr'ous Workmentioning

confidence: 69%

A laboratory assessment of the relative importance of turbulence, particle composition, and concentration in limiting maximal floc size and settling behaviour

Milligan

Hill

1998

Journal of Sea Research

113

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“…Beyond the microbial impact on surface stability, the lateral movement of sediment can be severely influenced during bedform development and migration (Friend et al 2008;Hagadorn and McDowell 2012;Malarkey et al 2015;Parsons et al 2016) but this phenomenon is also highly significant for the erosion thresholds of deeper sediment layers (Gerbersdorf et al 2007;Chen et al 2017). Last but not least, EPS has been shown to promote the aggregation and deposition of suspended material (Eisma 1986;Mietta et al 2009;Manning et al 2010). Consequently, microbes and their biofilm matrix impact the whole ETDC (erosion-transport-deposition-consolidation) cycle of fine sediments.…”

Section: Is Sediment Biostabilisation Important?mentioning

confidence: 99%

“…Organic quantification methods may therefore provide a good predictor variable for floc behaviour and settling velocity. The results undoubtedly have important implications for future models, since SPM concentration and turbulence are often considered to mediate flocculation and depositional behaviour alone (Eisma 1986) while biological properties are, more often than not, excluded, but undoubtedly increase the cohesive force between particles (Mietta et al 2009). …”

Section: Field Observationsmentioning

confidence: 99%

Form, function and physics: the ecology of biogenic stabilisation

et al. 2018

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Purpose The objective of this work is to better understand the role that biological mediation plays in the behaviour of fine sediments. This research is supported by developments in ecological theory recognising organisms as Becosystem engineers^and associated discussion of Bniche construction^, suggesting an evolutionary role for habitat modification by biological action. In addition, there is acknowledgement from engineering disciplines that something is missing from fine sediment transport predictions. Materials and methods Advances in technology continue to improve our ability to examine the small-scale 2D processes with large-scale effects in natural environments. Advanced molecular tools can be combined with state-of-the-art field and laboratory techniques to allow the discrimination of microbial biodiversity and the examination of their metabolic contribution to ecosystem function. This in turn can be related to highly resolved measurements and visualisation of flow dynamics. Results and discussion Recent laboratory and field work have led to a paradigm shift whereby hydraulic research has to embrace biology and biogeochemistry to unravel the highly complex issues around on fine sediment dynamics. Examples are provided illustrating traditional and more recent approaches including using multiple stressors in fully factorial designs in both the laboratory and the field to highlight the complexity of the interaction between biology and sediment dynamics in time and space. The next phase is likely to rely on advances in molecular analysis, metagenomics and metabolomics, to assess the functional role of microbial assemblages in sediment behaviour, including the nature and rate of polymer production by bacteria, the mechanism of their influence on sediment behaviour. Conclusions To fully understand how aquatic habitats will adjust to environmental change and to support the provision of various ecosystem services, we require a holistic approach. We must consider all aspects that control the distribution of sediment and the erosion-transport-deposition-consolidation cycle including biological and chemical processes, not just the physical. In particular, the role of microbial assemblages is now recognised as a significant factor deserving greater attention across disciplines.

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“…In general, flocs were classified as two types, namely, microflocs and macroflocs, whereas cohesive sediment flocculates to form small microflocs first, and then macroflocs by combining the microflocs (Eisma 1986). Microflocs can be classified as those aggregates which do not exceed a spherically equivalent diameter of 100 µm (Lafite 2001) and have a settling velocity of less than 1 mm/s.…”

Section: Introductionmentioning

confidence: 99%