نتایج جستجو برای: sediment particles

تعداد نتایج: 191589  

2016
Hayato Watanabe Miku Ito Akira Matsumoto Hisayuki Arakawa

Kelp forests on coastal rocky shores are negatively impacted by sudden sediment loads that can occur with storms and floods. Using laboratory experiments, we studied the effects of sediment deposition on the survival of the large brown alga Eisenia bicyclis juveniles (zoospores and gametophytes) to quantify the potential impacts of particulate matter on kelp forests. The zoospore adhesion rate ...

2007
H. S. Woo P. Y. Julien E. V. Richardson

Existing methods based on the diffusion theory have been extended to determine the sediment concentration distribution for large concentrations of sand. The modifications for volumetric concentrations ranging from 4 to 20% include decreased fall velocity, and increased viscosity and specific weight of the suspension. The sediment concentration profiles are sensitive to the velocity profiles and...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2009
Vamsi Ganti Arvind Singh Paola Passalacqua Efi Foufoula-Georgiou

Following the introduction of the Brownian motion model for sediment transport by Einstein, several stochastic models have been explored in the literature motivated by the need to reproduce the observed non-Gaussian probability density functions (PDFs) of the sediment transport rates observed in laboratory experiments. Recent studies have presented evidence that PDFs of bed elevation and sedime...

Journal: :Applied and environmental microbiology 2008
Colin R Jackson Andrew Q Weeks

Bacterial communities associated with sediment particles were examined using PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequencing. Particle size influenced community structure, with attached bacterial assemblages separating into 63- to 125-, 125- to 1,000-, and 1,000- to 2,000-microm fractions. Differences were particularly pronounced for the Verrucomicrobia-Planctomycetes, ...

Journal: :Journal of environmental quality 2005
J Gan S J Lee W P Liu D L Haver J N Kabashima

Pyrethroids are commonly used insecticides in both agricultural and urban environments. Recent studies showed that surface runoff facilitated transport of pyrethroids to surface streams, probably by sediment movement. Sediment contamination by pyrethroids is of concern due to their wide-spectrum aquatic toxicity. In this study, we characterized the spatial distribution and persistence of bifent...

Journal: :Revista de biologia tropical 2003
K Kathiresan

The mangrove forests play a significant role as sediment traps. They reduce tidal flows and induce sedimentation of soil particles at low tide. However, there are no such processes taking place in the non-mangrove areas. Site of Avicennia-Rhizophora interphase is more efficient than Avicennia and or Rhizophora zones, in trapping the sediment by 30, 25 and 20% respectively at low tide as compare...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2009
I B Ramsteiner K E Jensen D A Weitz F Spaepen

We present a confocal microscopy study of 1.55 microm monodisperse silica hard spheres as they sediment and crystallize at the bottom wall of a container. If the particles sediment onto a feature less flat wall, the two bottom layers crystallize simultaneously and layerwise growth follows. If the wall is replaced by a hexagonal template, only layerwise growth occurs. Our results complement earl...

Recognition of origin of sand dunes is very important in wind erosion control projects. Because of many problems associated with traditional procedures for identifying sediment sources, fingerprinting techniques, based on physical, chemical and organic properties of sediment and source materials, are increasingly being used as a valuable and effective alternative approach to assembling such inf...

2015
H. Kobus

nozzle and sediment determ ines the rate of scour . Under fully turbulent conditions, the re la~ive dimensions of the sccur hole d (:pend onl y upon the t ime pa rame ter and the ratio between the fictitious axial jer velocity a t the bed and the fa ll ve locity of the sediment particles. There exist two distinct values of this ratio, at which the eroding action of the jet becomes particularly ...

Journal: :ecopersia 2014
soheila aghabeigi amin hamid reza moradi bakhtiar fattahi

soil erosion is an abstruse phenomenon which contains segregation and transmission of soil particles and runoff from rainfall and infiltration. runoff and sediment generation was compared using rainfall simulator in grassland (st. parviflora-br. tomentellus) and shrubland (as. parrowianus-as. gossipinus). for this purpose, vegetation map was supplied for two vegetation types four main aspects a...

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