Transport of adsorbing metals from stream water to a stationary sand-bed in a laboratory flume

1995 ◽  
Vol 46 (1) ◽  
pp. 209 ◽  
Author(s):  
H Eylers ◽  
NH Brooks ◽  
JJ Morgan
Keyword(s):  
Metal Ions ◽  
Stream Water ◽  
Flow Conditions ◽  
Advective Flow ◽  
Flume Experiments ◽  
Lithium Ions ◽  
Overlying Water ◽  
Experimental Conditions ◽  
Sediment Bed ◽  
Laboratory Flume

The transport of zinc and lithium ions between the overlying water column and the stationary sand-bed in a laboratory flume with bottom bedforms is investigated. Experiments have been performed under simplified conditions in a recirculating laboratory flume with straight impermeable walls and a sand-bed. The sand is well sorted and acid-washed to provide reproducible experimental conditions. The chemical composition of the recirculating water is controlled and steady flow conditions are maintained in the experiments. The concentrations of initially added metal ions are monitored both in the circulating overlying water and in the pore water of the sediment bed. Batch experiments were performed to investigate the chemical partitioning of the metal ions to the sand grain surfaces, and the data were compared with adsorption values obtained from the flume experiments. A model based on pressure-driven advective flow and linear partitioning of the pollutant to the sediment has been developed and accurately predicts the rate of transfer of the metal ions (zinc and lithium) into the bed in the case of stationary bedforms.

scholarly journals Erosion of fine sediments from a rough bed

2018 ◽  
Vol 40 ◽  
pp. 05058
Author(s):  
Michele Trevisson ◽  
Olivier Eiff
Keyword(s):  
Shear Stress ◽  
Sediment Supply ◽  
Critical Conditions ◽  
Bed Shear Stress ◽  
Flow Conditions ◽  
Flume Experiments ◽  
Gravel Beds ◽  
Fine Sediments ◽  
Sediment Bed ◽  
Rough Bed

Gravel beds in river systems represent important aquatic habitats, which may be endangered by the introduction of large amounts of fine sediments. In order to better understand the interaction between fine sediments and coarse immobile beds in sediment supply-limited systems, a series of flume experiments was conducted. The main goal was to determine under what conditions erosion stops. The experiments were performed over a bed of regularly arranged spheres. Plastic particles were taken as sediment and the erosion was investigated under uniform flow conditions for variable bed shear stress conditions just above critical conditions. The system was observed to behave in two different ways: with higher bed shear stress fine sediments were completely washed out, whilst with lower stress the sediment bed reached a stable level just above the equator of the spheres.

scholarly journals Deposition of Cryptosporidium Oocysts in Streambeds

2006 ◽  
Vol 72 (3) ◽  
pp. 1810-1816 ◽  
Author(s):  
Kristin E. Searcy ◽  
Aaron I. Packman ◽  
Edward R. Atwill ◽  
Thomas Harter
Keyword(s):  
Surface Water ◽  
Surface Waters ◽  
Colloidal Particles ◽  
Suspended Sediments ◽  
Flume Experiments ◽  
Streams And Rivers ◽  
Sediment Bed ◽  
Physicochemical Interactions ◽  
Cryptosporidium Oocysts ◽  
Laboratory Flume

ABSTRACT The transfer of Cryptosporidium oocysts from the surface water to the sediment beds of streams and rivers influences their migration in surface waters. We used controlled laboratory flume experiments to investigate the deposition of suspended Cryptosporidium parvum oocysts in streambeds. The experimental results demonstrate that hydrodynamic interactions between an overlying flow and a sediment bed cause oocysts to accumulate in the sediments and reduce their concentrations in the surface water. The association of C. parvum with other suspended sediments increased both the oocysts' effective settling velocity and the rate at which oocysts were transferred to the sediment bed. A model for the stream-subsurface exchange of colloidal particles, including physical transport and physicochemical interactions with sediment grains, accurately represented the deposition of both free C. parvum oocysts and oocysts that were attached to suspended sediments. We believe that these pathogen-sediment interactions play an important role in regulating the concentrations of Cryptosporidium in streams and rivers and should be taken into consideration when predicting the fate of pathogens in the environment.

An Experimental Study on the Transport of Sediment in Sewer Pipes with a Permanent Deposit

1992 ◽  
Vol 25 (8) ◽  
pp. 115-122 ◽  
Author(s):  
G. S. Perrusquía
Keyword(s):  
Experimental Study ◽  
Critical Shear Stress ◽  
Side Wall ◽  
Bedload Transport ◽  
Flow Conditions ◽  
Sewer Pipes ◽  
Sediment Bed ◽  
Concrete Pipe ◽  
Geometric Factors ◽  
Particle Parameters

An experimental study of the transport of sediment in a part-full pipe was carried out in a concrete pipe. The experiments were confined to bedload transport. The purpose of this study was to analyze the flow conditions that characterize the stream traction in pipe channels and their relationship to flow resistance and sediment transport rate. Three procedures used in this kind of experimental study were tested and found valid: 1) the vertical velocity distribution near the sediment bed can be described by the velocity-defect law, 2) the side wall elimination procedure can be used to compute the hydraulic radius of the sediment bed, and 3) the critical shear stress of the sediment particles can be obtained by using Shields' diagram. A relationship to estimate bedload transport, based on dimensional analysis, was proposed. This was expressed in terms of both flow and particle parameters as well as geometric factors. Further experimental work is recommended before this relationship can be fully incorporated in a simulation model for the analysis of storm sewers.

Debris flow impact on a flexible barrier: laboratory flume experiments and force-based mechanical model validation

2021 ◽  
Vol 106 (1) ◽  
pp. 735-756
Author(s):  
R. Brighenti ◽  
L. Spaggiari ◽  
A. Segalini ◽  
R. Savi ◽  
G. Capparelli
Keyword(s):  
Debris Flow ◽  
Model Validation ◽  
Mechanical Model ◽  
Flume Experiments ◽  
Flexible Barrier ◽  
Laboratory Flume

scholarly journals Flume experiments on vegetated alternate bars

2018 ◽  
Vol 40 ◽  
pp. 02034 ◽  
Author(s):  
Giulio Calvani ◽  
Simona Francalanci ◽  
Luca Solari
Keyword(s):  
Hydrological Regime ◽  
Spatial Arrangement ◽  
Flume Experiments ◽  
Rigid Vegetation ◽  
Hydraulic Conditions ◽  
Laboratory Flume ◽  
Alternate Bars ◽  
River Reach ◽  
Bed Slope ◽  
And Migration

The planform morphology of a river reach is the result of the combined actions of sediment motion (erosion, transport and deposition), hydrological regime, development and growth of vegetation. However, the interactions among these processes are still poorly understood and rarely investigated in laboratory flume experiments. In these experiments and also in numerical modelling, vegetation is usually represented by rigid cylinders, although it is widely recognized that this schematization cannot reproduce the effects of root stabilization and binding on riverbed sediment. In this work, we focus on the effects of added vegetation on morphological dynamics of alternate bars in a straight channel by means of flume experiments. We performed laboratory experiments reproducing hydraulic conditions that are typical of gravel bed rivers, in terms of water depth, bed slope and bed load; these conditions led to the formation of freely migrating alternate bars. We then employed rigid vegetation that was deployed on the reproduced alternate bars according to field observations. Various vegetation scenarios, in terms of density and spatial arrangement, were deployed in the flume experiments such to mimic different maintenance strategies. Results show the effects of rigid vegetation on the alternate bar configuration on the overall topographic pattern, the main alternate bar characteristics (such as amplitude and wavelength) and migration rate.

scholarly journals Evaluating a Laboratory Flume Microbiome as a Window Into Natural Riverbed Biogeochemistry

2021 ◽  
Vol 3 ◽  
Author(s):  
Matthew H. Kaufman ◽  
John G. Warden ◽  
M. Bayani Cardenas ◽  
James C. Stegen ◽  
Emily B. Graham ◽  
...  
Keyword(s):  
16S Rrna Gene Sequencing ◽  
Spatiotemporal Variability ◽  
Rrna Gene ◽  
Natural Ecosystems ◽  
Flume Experiments ◽  
Riverbed Sediments ◽  
Laboratory Flume ◽  
Curtis Dissimilarity ◽  
The Common ◽  
Rrna Gene Sequencing

Riverbeds are hotspots for microbially-mediated reactions that exhibit pronounced variability in space and time. It is challenging to resolve biogeochemical mechanisms in natural riverbeds, as uncontrolled settings complicate data collection and interpretation. To overcome these challenges, laboratory flumes are often used as proxies for natural riverbed systems. Flumes capture spatiotemporal variability and thus allow for controlled investigations of riverbed biogeochemistry. These investigations implicitly rely on the assumption that the flume microbiome is similar to the microbiome of natural riverbeds. However, this assumption has not been tested and it is unknown how the microbiome of a flume compares to natural aquatic settings, including riverbeds. To evaluate the fundamental assumption that a flume hosts a microbiome similar to natural riverbed systems, we used 16s rRNA gene sequencing and publicly available data to compare the sediment microbiome of a single large laboratory flume to a wide variety of natural ecosystems including lake and marine sediments, river, lake, hyporheic, soil, and marine water, and bank and wetland soils. Richness and Shannon diversity metrics, analyses of variance, Bray-Curtis dissimilarity, and analysis of the common microbiomes between flume and river sediment all indicated that the flume microbiome more closely resembled natural riverbed sediments than other ecosystems, supporting the use of flume experiments for investigating natural microbially-mediated biogeochemical processes in riverbeds.

Laboratory Studies of the Effects of Dissolved Organic Material on the Adsorption of Organochlorine Pesticides by Sediments and Transport in Rivers

1993 ◽  
Vol 28 (8-9) ◽  
pp. 199-208 ◽  
Author(s):  
J.-Y. Ding ◽  
S.-C. Wu
Keyword(s):  
Organic Matter ◽  
Molecular Diffusion ◽  
Transport Model ◽  
Water System ◽  
High Rate ◽  
Sensitivity Analyses ◽  
Overlying Water ◽  
Sediment Bed ◽  
Three Phase ◽  
Phase Transport

In this study experiments simulating sediment/water system were carried on with sediments spiked with aldrin, heptachlor epoxide and p,p'-DDE. It was expected that these hydrophobic contaminants would be released to the overlying water column from sediment bed with molecular diffusion and co-diffusion with dissolved organic matter (DOM) as well. A three-phase-transport model including aqueous, solid and mobile adsorptive phases was developed and used to describe the behavior of these contaminants and to explain the results of the experiments. Sensitivity analyses show that observable effects of DOM occur only under conditions of high partition coefficient (Koc) of the contaminant and high rate of transfer from sediment organic matter to DOM. In this study, owing to the low concentration of DOM and relatively low hydrophobicity of the compounds, the DOM-associated pollutant flux does not significantly contribute to the total flux. Also, the simulated results of the model can reasonably explain the variations of the concentrations of the spiked compounds observed in the microcosms.

scholarly journals Uremic platelets have a functional defect affecting the interaction of von Willebrand factor with glycoprotein IIb-IIIa

Blood ◽  
1990 ◽  
Vol 76 (7) ◽  
pp. 1336-1340 ◽  
Author(s):  
G Escolar ◽  
A Cases ◽  
E Bastida ◽  
M Garrido ◽  
J Lopez ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Indirect Evidence ◽  
Flow Conditions ◽  
Experimental Conditions ◽  
Shear Rates ◽  
Functional Defect ◽  
Uremic Patients ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Uremic patients have an impaired platelet function that has been related to membrane glycoprotein (GP) abnormalities. Using a perfusion system, we have studied the interaction of normal and uremic platelets with vessel subendothelium (SE) under flow conditions. Reconstituted blood containing washed platelets, purified von Willebrand factor (vWF) (1 U/mL), and normal washed red blood cells was exposed to de- endothelialized rabbit segments for 10 minutes at two different shear rates (800 and 1,600 seconds-1). In some experiments a monoclonal antibody to the GPIIb-IIIa complex (EDU3) was added to the perfusates. With normal platelets, the percentage of the vessel covered by platelets (%CS) was 23.1% +/- 3.7% at 800 seconds-1 and 30% +/- 4.3% at 1,600 seconds-1. Platelets were observed in contact or forming monolayers on vessel SE. EDU3 inhibited the spreading of normal platelets. The %CS (11.1% +/- 3.3%) was statistically decreased (P less than .01) and most of the platelets were observed in contact with the vessel surface. These data indicate that, under flow conditions, the interaction of vWF with GPIIb-IIIa can support the spreading of normal platelets in the absence of exogenous fibrinogen. Under the same experimental conditions, the interaction of uremic platelets with SE was markedly impaired at both shear rates studied (P less than .01 v normal platelets). The presence of EDU3 did not modify the interaction of uremic platelets. These results confirm the impairment of the platelet adhesion observed in uremic patients. Furthermore, they indicate the presence of a functional defect in the interaction of vWF with GPIIb-IIIa. The fact that perfusions with normal and uremic platelets in the presence of an antibody to the GPIIb-IIIa complex did not show any differences gives indirect evidence on a functionally normal interaction vWF/GPIb in uremic patients.

scholarly journals In Situ Magnetite Formation and Long-Term Arsenic Immobilization under Advective Flow Conditions

2016 ◽  
Vol 50 (18) ◽  
pp. 10162-10171 ◽  
Author(s):  
Jing Sun ◽  
Steven N. Chillrud ◽  
Brian J. Mailloux ◽  
Benjamin C. Bostick
Keyword(s):  
Flow Conditions ◽  
Advective Flow ◽  
Magnetite Formation
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