In many gravel-bedded rivers, floods that fill the channel banks create just enough shear stress to move the median-sized gravel particles on the bed surface (D50). Because this observation is common and is supported by theory, the coincidence of bankfull flow and the incipient motion of D50 has become a commonly used assumption. However, not all natural gravel channels actually conform to this...

The ability to achieve meaningful decreases in sediment loads to reservoirs requires a determination of the relative importance of sediment sources within the contributing basins. In an investigation of sources of fine-grained sediment (clay and silt) within the Perry Lake Basin in northeast Kansas, representative samples of channel-bank sources, surface-soil sources (cropland and grassland), a...

Sediment traps were used to evaluate the frequency, cause, and relative intensity of sediment mobility/resuspension along the fringing coral reef off southern Molokai (February 2000-May 2002). Two storms with high rainfall, floods, and exceptionally high waves resulted in sediment collection rates>1000 times higher than during non-storm periods, primarily because of sediment resuspension by wav...

Depth profiles of oxygen concentration and the redox status of acid-extractable iron were measured in littoral sediment cores of Lake Constance after mechanical removal of surface sediment, mixing, and re-deposition. In undisturbed sediment cores, oxygen penetrated down to 2.9±0.4 mm or 4.6±0.4 mm depth, respectively, after 12 h of incubation in the dark or light; causing a net diffusive flux o...

Seasonal and spatial distributions of cadmium (Cd) and organic matter (OM) in sediment and suspended matter of the semi-enclosed Kaštela Bay (middle Adriatic Sea) were investigated at four stations during a one year period (April 2000 April 2001). Samples of surface sediment and suspended matter were collected monthly. One sediment core was sampled at every station at the beginning of the sampl...

The present work was planned to evaluate the phytoextraction of metal mine tailings, Sarcheshmeh copper mine, SE of Iran, by the endemic plant species Medicago sativa L. (Alfalfa). In this pot experiment, we investigated the effects of seven amendments on the growth of alfalfa and uptaking metals from the mine tailings and stream sediment of tailing dam surface. The mean metal concentrations in...

Sediments play a key role in the marine nitrogen cycle and can act either as a source or a sink of biologically available (fixed) nitrogen. This cycling is driven by a number of microbial remineralization reactions, many of which occur across the oxic/anoxic interface near the sediment surface. The presence and activity of large burrowing macrofauna (bioturbators) in the sediment can significan...

Our objectives are to examine sediment PAH distributions in environments representing contrasting depositional regimes within the York River, VA, a sub-estuary of the Chesapeake Bay. Our study utilizes a suite of geochemical tools to quantify sediment processes influencing the distribution of dissolved and solid-phase PAHs. These tools will enable us to quantify particle residence times in surf...

abstract bottom rack intake is one of the most appropriate structures for diverting water in steep rivers. the problems of corrosion, deformity and clogging of the bottom racks in long term, inspires a new system of bottom intake in which a filled trench of porous media is replaced by the bottom racks. diversion of a specified amount of discharge through the porous media when void space in the ...