Evaluation of the Role of Silt Content on the Flocculation Behavior of Clay‐Silt Mixtures

Xu, Conghui; Odum, Bismark; Chen, Yongping; Yao, Peng

doi:10.1029/2021wr030964

Cited by 5 publications

(2 citation statements)

References 55 publications

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“…Thus, both sediment S1 and S2 are considered noncohesive. Meanwhile, previous settling experiments also showed no flocculation for suspended silt (te Slaa et al, 2013;te Slaa et al, 2015;Xu et al, 2022). Furthermore, Yao et al (2022a) discovered that silty sediment with grain size larger than 8 μm does not flocculate in freshwater (0‰ of salinity), which is consistent with our experimental phenomena.…”

Section: Casesupporting

confidence: 91%

Wind effect on sediment suspensions over silt-dominated mixtures: An experimental study

Chen

Zhu

et al. 2023

Front. Mar. Sci.

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A series of laboratory experiments have been conducted to explore the wind effect on Sediment Suspended Concentrations (SSCs) in fine-grained coastal systems. The paddle waves were overplayed with surface-blowing winds in a wind-wave flume to mimic offshore swells coupling with local wind waves during rough weather. Both SSCs and water turbulences under different wind and wave conditions have been investigated over two kinds of sediment beds (Sediment 1, S1, D50 = 52µm and Sediment 2, S2, D50 = 90µm). The High Concentration Layers (HCL) were formed under most of the wave-only conditions, while with the introduction of the stronger wind, more sediment suspensions were transported upward, increasing SSCs in upper water elevations. The finer sediment S1 is easier to suspend than S2 under the same conditions. The enhancement of the vertical turbulence intensity (σw) by winds is the main reason for the increase in SSCs. Meanwhile, because the wind-induced turbulence can hardly penetrate the HCL, the turbulence intensities outside the HCL can be further amplified compared to the experiment without a sediment bed. The wind contributes over 65% of the SSC enlargement above the HCL under a wind of 10m/s for S1, while less than 20% inside the HCL in most wind conditions. The sediment mixing coefficient (ϵs), a crucial parameter for suspended sediment modeling, was enhanced with stronger winds. Although the existing formulas for the vertical distribution of ϵs are valid under both wave-only and small winds (2.5 m/s) for both sediment beds, the enhancement of ϵs caused by strong winds cannot be captured, requiring further research.

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Section: Casesupporting

confidence: 91%

Wind effect on sediment suspensions over silt-dominated mixtures: An experimental study

Chen

Zhu

et al. 2023

Front. Mar. Sci.

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“…An experimental investigation conducted by Tran and Strom (2017) on the settling behavior of clay and silt mixtures indicated that silt particles, independent of their size, could become bound within clay flocs and that the silt content had no significant effect on floc size. However, the trapping of silt particles within flocs can have an important impact on floc density, and thus on the settling velocity which may increase by more than 50% (Tran & Strom, 2017; Xu et al., 2022). These results were confirmed by river studies (Osborn et al., 2023) and agree with Droppo and Ongley (1994), indicating that salinity is not a needed for sediments to flocculate.…”

Section: Discussionmentioning

confidence: 99%

From Particles to Flocs: Revealing Where Flocculation Occurs in the Nearfield of a Negatively‐Buoyant River Plume in a Large Lake (Lake Geneva)

Piton,

Lemmin,

Bourrin

et al. 2024

JGR Oceans

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The dynamics of sediments entering lakes in river plumes is virtually unknown. This field study provides unprecedented evidence of the initiation and evolution of suspended sediment flocculation in the nearfield of the negatively‐buoyant Rhône River plume, flowing as interflow in the thermocline of stratified Lake Geneva. Sediment floc property changes (formation, size, composition, shape) with depth and distance from the mouth, were determined by combining digital holographic camera LISST‐HOLO data with full‐depth in situ profiles of particle size (LISST‐100X), density, turbidity, currents and water samples taken along the plume path. The total suspended matter volume of inflowing Rhône River waters (∼155 mg l−1) mostly consisted of clays (<4 μm), very fine silts (4–8 μm) and small contributions of microflocs (20–100 μm). This composition was also found in the interflow plume core. Above the plume, in the epilimnion, fine silts, microflocs and numerous phytoplanktonic organisms (∼200 μm) were observed, representative of the lake background. High levels of shear (15–27 s−1) and turbulence occurred in the shear layer that formed between the interflow bottom and the hypolimnion below. It was found that macroflocs only formed in this shear layer. In the hypolimnion, sediment load was the lowest and macroflocs (up to ∼300 μm) composed of inorganic particles were dominant. The size of the largest flocs was limited by the size of the smallest turbulent eddies determined by the Kolmogorov microscale. Floc 3D fractal dimensions of ∼2.1–2.5 suggest an intermediate shape complexity between marine snow and sludge flocs.

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The influence of turbulence on sediment phosphorus sorption

Zhu

Chen

et al. 2023

Ecotoxicology and Environmental Safety

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Evaluation of the Role of Silt Content on the Flocculation Behavior of Clay‐Silt Mixtures

Cited by 5 publications

References 55 publications

Wind effect on sediment suspensions over silt-dominated mixtures: An experimental study

Wind effect on sediment suspensions over silt-dominated mixtures: An experimental study

From Particles to Flocs: Revealing Where Flocculation Occurs in the Nearfield of a Negatively‐Buoyant River Plume in a Large Lake (Lake Geneva)

The influence of turbulence on sediment phosphorus sorption

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