The paper considers results of experimental studies of sediments dynamics in regions of density stratification (river mouth areas) and thermal stratification (lakes). The studies were carried out using fluorescent tracers (FT). A method of preparing fluorescently labeled natural sediment particles is described. The sediments are taken from appropriate sites (river bed, lake bottom) and tagged with various colored stains, which can be adjusted to last for specified times varying from 10 days to 6-7 months. Separate size fractions of the bottom sediments are dyed (several colors) and reloaded close to the sampling sites. Then they are traced "downstream". The tracers are ecologically harmless. They have the same hydrodynamic properties as the original sediment particles and can be detected with high sensitivity. For quantitative measurements, three methods were developed, based on: 1) visual scanning and counting; 2) excitation emission fluorescence spectroscopy; 3) optical absorption of extracts in organic solutions. The 3-dimensional fluctuations of the velocity vector were measured in parallel. The results of these studies allowed us to estimate the main directions of the sediment transfer along the bottom slope and in the water column in the Lakes. Specifically for Lake Kinneret, these data revealed prevailing of the longshore sediment transport in the littoral of Lake Kinneret. They evidenced events of the sediment vertical transport through thermocline. The resuspended particles (silts and sands) are transported also horizontally along entire water column by Make currents. Based on analysis of the heterogeneity of the vertical distribution of resuspension, two mechanisms of resuspended sediment transfer in a stratified water mass have been proposed. A previously developed model (accounting for the bottom sediment size distribution, bottom slope steepness and wave activity) was applied to analyze these data. The model helped us estimate effects of the lake water level fluctuations on directions of the resuspended matter transport along the bottom slope. Field experimental measurements made at the river mouths show that suspended matter (SM) concentration (SMC) decreases along the jet flow. This SMC decrease is governed by two main factors. The first one is the SM sedimentation due to the flow velocity attenuation along the jet flow. The second factor is the SMC dilution, produced by the turbulent mixing of the jet (river) water (having a high SMC) with the sea water mass (with a much lower SMC).
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