Effect of salinity on the settling velocity of fine sediments of a harbour basin

• DOI: 10.2112/si65-201.1
• Publication Date: 2016-02-10T11:48:43Z
• Authors: Luis Ivens Portela; Susana Ramos; António Trigo Tei...
• Keywords: Settling; Silt; Illite

Portela, L.I., Ramos, S. and Trigo-Teixeira, A., 2013. Effect of salinity on the settling velocity fine sediments a harbour basin. In: Conley, D.C., Masselink, G., Russell, P.E. O'Hare, T.J. (eds.)Salinity is known to increase cohesion clay minerals, thus flocculation fine-grained in suspension. However, influence natural particles often unclear, due organic biological aggregation other controlling factors. This paper examines effect collected basin Tagus estuary. The sediment sample consists silt- clay-sized (D10 = 2 μm; D50 9 D90 37 μm). Quartz main constituent illite mineral. experiments were conducted 2.25-m high column, for constant initial concentration (1.5 g l−1) different values (0, 5, 10, 15 30). During each experiment, samples at 10 vertical levels time instants. Settling velocities calculated basis time- evolution suspended concentrations. At start experiments, after cessation turbulence, increased direct relation with salinity, maximum ranging between 0.3 mm s−1 under freshwater conditions 0.9 30. After 5 hours, proportion remaining suspension was 45% only about 10% salinities Using mass-weighted mean describe deposition fluxes, it concluded that increases by factor 6.5 marine conditions.