نتایج جستجو برای: bed sediments

تعداد نتایج: 77010  

Journal: :Journal of the Air & Waste Management Association 2002
Raghunathan Ravikrishna Kalliat T Valsaraj Louis J Thibodeaux Cynthia B Price James M Brannon Sally Yost

Remedial dredging of contaminated bed sediments in rivers and lakes results in the suspension of sediment solids in the water column, which can potentially be a source for evaporation of hydrophobic organic compounds (HOCs) associated with the sediment solids. Laboratory experiments were conducted in an oscillating grid chamber to simulate the suspension of contaminated sediments and flux to ai...

ژورنال: اکوبیولوژی تالاب 2019
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Precise study of geophysical and ecological characteristics of benthic habitats is very important, because the seabed type of these habitats has close relationship with presence or absence of particular benthic species as well as with their distribution in the benthic communities. The aim of this study was Investigation of Relationship between Ecogeomorphology and Granulometry of Bed Sediments ...

Journal: :Earth Surface Processes and Landforms 2023

The origin of the well-known ‘grain size gap’ within range 1–10 mm in fluvial gravels is explored a laboratory experiment to ascertain effect hydraulic sorting. A widely graded sand/gravel mixture was fed into flume containing bed composed same sediment mixture. rate feed varied but water flow remained constant throughout at that sustained size-selective bedload transport with negligible suspen...

2007
DOUGLAS R. MACAYEAL

Recent seismic studies of ice stream B, Antarctica and field analysis of mid-latitude glacial deposits suggest that deformable basal sediments (e.g., water-saturated till) are important in determining ice sheet flow. If the ratio of till viscosity to effective ice viscosity is small, vertical shear associated with horizontal flow is confined to the deforming bed alone. Ice flow over a deformabl...

2008
Jeffrey A. Nittrouer Mead A. Allison Richard Campanella

[1] New methods of data collection and processing are developed to provide quantitative, reach-scale measurements of bedform transport mass within the tidally influenced Mississippi River. A multibeam swath profiler was used to collect daily bathymetry over a range of water discharges, and bed elevation changes induced by dune migration are measured. These values are coupled with bulk physical ...

2007
S. Neuhuber M. Wagreich I. Wendler C. Spötl

Several transitions of Lower to Middle Turonian pelagic marl–limestone-cycles into Oceanic Red Beds were studied at high resolution to gain a better understanding of the Tethyan marine system before and during red bed initiation and development. Samples were analysed for mineralogy, geochemistry, and stable isotope composition. In particular, carbonate geochemistry of diagenetically largely una...

2012
Y. Xiong V. J. Alarcon J. L. Martin W. H. McAnally

In this study, a stand-alone sediment and contaminant model, SEDDEER (Sediment Deposition and Erosion), is presented. The model simulates one water box and underlying (multiple) sediment bed layers, and was developed for incorporation into water quality models. The processes incorporated in the model are: settling and deposition, resuspension, equilibrium adsorption/desorption, sediment-water i...

Journal: :Geophysical Research Letters 2022

The sediment composition of the seabed governs its mobility, hence determining transport and morphological evolution estuaries tidal basins. Bed sediments often consist mixtures sand mud, with spatial gradients in sand/mud content. This study aims at increasing understanding processes driving basins, focusing on depositional processes. We show that bed Wadden Sea tend to be either mud-dominated...

2014
Simone D. Langhans Klement Tockner

Understanding complex, dynamic, and diverse ecosystems is essential for developing sound management and conservation strategies. Gravel-bed river floodplains are composed of an interlinked mosaic of aquatic and terrestrial habitats hosting a diverse, specialized, and endangered fauna. Therefore, they serve as excellent models to investigate the biodiversity of multiple ecotones and related edge...

Journal: :Environmental monitoring and assessment 2008
E Alkhatib E Berna

Arsenic released by bottom sediments was determined by experiments in which the sediments were artificially re-suspended using a particle entrainment simulator (PES) to simulate river conditions. Sediment cores were collected from various tributaries to drinking water reservoirs in Connecticut spiked with arsenic, and run in the PES at simulated bed-flow shear stresses from 0.0 to 0.6 N/m(2). U...

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