Theoretically, if in calm waters only gravitation were used as th

Theoretically, if in calm waters only gravitation were used as the dominant force, it would be possible to determine what percentage of particles of a specified diameter would settle and which particles would have a velocity too low to ensure settlement. An example of such an approach was given by Imam et al. (1983), who established

the vertical velocity field using a finite difference model of the vorticity transport stream function equations with a constant eddy viscosity. The eddy viscosity is obtained by applying a theoretical model. That is, in order to determine the sedimentation rate other theoretical assumptions should be made; hence, sedimentation has a complex nature, even under idealised theoretical conditions. The main reason for this is that sedimentation, besides its complicated nature, is a highly nonlinear and unstable phenomenon (wave and current forcing) and therefore difficult to subject to rigorous mathematical treatment. Any attempt at describing sedimentation processes requires the

simultaneous identification of the mechanisms governing sediment deposition, erosion and the evolution of a number of morphological seabed forms (Pruszak, 1990, Pruszak, 1998 and Komar, 1998). The rate of sediment accumulation in water basins depends on a number of factors, such as the quantity and quality of sediment being deposited, distance from sediment source, intensity of biological processes (e.g. phytoplankton blooms, bioturbation), seasonal phenomena (e.g. Sotrastaurin ic50 phytoplankton blooms,

autumn and winter storm surges), geological seabed composition, depth of seabed and hydrological and hydrodynamic regimes. Moreover, the amount of sediment transported from land to sea may also be affected by the intensity of weathering, erosion and degradation. The sediment Staurosporine supply to Puck Bay from rivers varies seasonally. Sediment discharges peak in late January and early February and fall to a minimum between June and August (Szymczak, 2006 and Szymczak and Piekarek-Jankowska, 2006). In the southern Baltic Sea and the Gulf of Gdańsk it is estimated that the rate of accumulation ranges between 0.5 and 2 mm year− 1. The aim of this study was to determine the recent sediment deposition rate and sediment accumulation rate specific to seabed formation in the eastern part of Puck Bay using two methods: in situ sediment traps and radioisotopes. In order to describe adequately the deposition and accumulation processes, we applied two ways of expressing the rates: (1) the linear rate of accumulation, giving the depth of sediment layer deposited in unit time (linear accumulation rate – LAR), expressed in [mm year− 1] and, (2) the mass sediment accumulation, which quantifies the mass of sediment deposited in unit time on unit surface area (mass accumulation rate – MAR) expressed in [g m− 2 day− 1] or [g m− 2 year− 1] (Einsele, 2000, Syvitski, 2003 and Hille et al., 2006).

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