Transport experiments, sediment

Stafford, W. F. III. (1992). Boundary analysis in sedimentation transport experiments A procedure for obtaining sedimentation coefficient distributions using the time derivative of the concentration profile. Anal. Biochem. 203(2), 295-301. 

Stafford, W. F. (1992a). Boundary Analysis in Sedimentation Transport Experiments A Procedure for Obtaining Sedimentation Coefficient Distributions Using the Time Derivative of the Concentration Profile. Anal. Biochem. 203, 295-301. 

C. I. Steefel, S. Carroll, P. Zhao, S. Roberts (2003) Cesium migration in Hanford sediment A multisite cation exchange model based on laboratory transport experiments. J Contamin. 

The combination of small size, parthenogenesis and potential for cryptobiosis had led to the assumption that limno-terrestrial tardigrades should be cosmopolitan. However, the analysis of the most likely form of transport - wind - has barely been explored. A simple experiment run by Sudzuki (1972) showed that tardigrades and other microinvertebrates were rarely dispersed by wind speeds less than 2m/s over 2 months. In the Antarctic, Janiec (1996) and Nkem et al. (2006) found that most microinvertebrates are transported with sediment or habitat (moss, lichen) near ground level and over relatively short distances. Kristensen (1987) mentioned that Echiniscus sp. were common in raindrops or air plankton after Fohn storms in Greenland. ... 

Graf (l971) defined the right hand part of Equation 6-44 as the sediment rxrefficient Fortier and Scobey (1926) conducted extensive experiments on permissible canal velocities to understand the erosion and transportation of sediments. Their results are presented in Table 6 3. Their malrr conclusions which are stUl valid today, were... 

Research into the aquatic chemistry of plutonium has produced information showing how this radioelement is mobilized and transported in the environment. Field studies revealed that the sorption of plutonium onto sediments is an equilibrium process which influences the concentration in natural waters. This equilibrium process is modified by the oxidation state of the soluble plutonium and by the presence of dissolved organic carbon (DOC). Higher concentrations of fallout plutonium in natural waters are associated with higher DOC. Laboratory experiments confirm the correlation. In waters low in DOC oxidized plutonium, Pu(V), is the dominant oxidation state while reduced plutonium, Pu(III+IV), is more prevalent where high concentrations of DOC exist. Laboratory and field experiments have provided some information on the possible chemical processes which lead to changes in the oxidation state of plutonium and to its complexation by natural ligands. 

Thus, for particles with a similar density and shape, sinking rates increase with increasing diameter because of the decrease in surface area to volume ratio. As shown in Table 13-5, sand-sized grains reach the sediments in a few days, whereas clays can take centuries. If entrained in a current, sinking particles can also experience significant horizontal transport. 

Addition of fuel oil no. 2 to a laboratory marine ecosystem showed that the insoluble, saturated hydrocarbons in the oil were slowly transported to the sediment on suspended particulate material. The particulate material contained 40-50% of the total amount of aliphatics added to the system and only 3-21% of the aromatic fraction (Oviatt et al. 1982). This indicates that most aromatic hydrocarbons are dissolved in the water (Coleman et al. 1984), whereas the aliphatic hydrocarbons are not (Gearing et al. 1980 Oviatt et al. 1982). In a similar experiment, when fuel oil no. 2 was added continuously to a marine ecosystem for 24 weeks, oil concentrations in the sediment remained low until 135 days after the additions began, but then increased dramatically to levels that were 9% of the total fuel oil added (108 g/tank) and 12% of the total fuel oil saturated hydrocarbons. The fuel oil concentrations in the sediment began to decrease quite rapidly after the maximum levels were reached. The highest sediment concentrations of saturated hydrocarbons (106-527 g/g) were found in the surface flocculent layer, with concentrations decreasing with sediment depth from 22 g/g to not detectable at 2-3 cm below the sediment surface. 

The transport of cysts via shellfish transplants or relays is even more difficult to evaluate. Not only is it possible that the sediment on the shells of seed shellfish contains cysts, but ingested cysts may even survive ingestion and germinate following defecation. Many cysts fed to soft-shell clams and mussels are viable following isolation from fecal pellets (35), but experiments have yet to be performed that mimic the conditions associated with prolonged residence in the intestines of shellfish during inter or intra-state transport. 

There are many transport conditions where experiments are needed to determine coefficients to be used in the solution. Examples are an air-water transfer coefficient, a sediment-water transfer coefficient, and an eddy diffusion coefficient. These coefficients are usually specific to the type of boundary conditions and are determined from empirical characterization relations. These relations, in turn, are based on experimental data. 

EXAMPLE 4.5 Laboratory experiments on mass transfer from sediments (similitude in mass transport)... 

Now, we need a boundary condition to determine /3i. This is difficult with suspended sediment profiles. We can develop a fairly good estimate of the distribution of suspended sediment once we have a known concentration at some location in the flow field. In the sediment transport field, bed load and suspended load are often discussed. The relation between the two, and some experience and measurements of both simultaneously, can be used to predict an equivalent suspended sediment concentration at the bed. Then, the relevant boundary condition of equation (E5.2.11) is... 

One of the most instructive fractionation procedures is the preparation of submitochondrial particles (SMPs). The particles are produced by soni-cation (see Experiment 4) and centrifugation. The pellet, which sediments between 12,000 and 100,000 X g after sonication, defines the submitochondrial particle fraction. Submitochondrial particles are actually chunks of inner membrane that have undergone circularization and inversion. In other words, the membrane has been turned inside-out. Essentially all of the components for electron transport are still present however, matrix enzymes are largely removed. 

Y. Nino, M.H. Garcia, Experiments on particle-turbulence interactions in the near-wall region of an open channel flow Implications for sediment transport, J. Fluid Mech. 326 (1996) 285-319. 

Experiments on transfer of submicrometre radioactive particles to smooth surfaces (Wells Chamberlain, 1967 Chamberlain et al., 1984) have shown that the dependency of vg on D213 holds over many orders of magnitude of D. This means that the transport by Brownian diffusion becomes progressively less effective as the particle size increases. For example a particle of 0.1 pm diameter has a diffusivity of 6.8 x 10 10 m2 s 1, a factor 1.2 x 104 smaller than that of I2 vapour. Since D does not depend on the particle density, it is appropriate to discuss transport by Brownian motion in terms of the particle diameter. The aerodynamic diameter, dA, is equal to dppp2 where pp is the particle density in c.g.s. units (g cm-3) not SI units (kg m-3), and is the appropriate parameter for particles with dp> 1 pm, for which impaction and sedimentation are the mechanisms of deposition. 

In 2001, the Netherlands Organization for Scientific Research (NWO) started a project called Chemically and electrically coupled transport in clayey soils and sediments to quantify the role of chemically and electrically coupled transport in clayey soils and to assess its relevance for the distribution and emission of contaminants and water. The project involves three Ph.D. students working on field and laboratory experiments and modelling of chemical-and electro-osmosis. 

Gagosian, R.B., Nigrelli, G.E., and Volkman, J.K. (1983) Vertical transport and transformation of biogenic organic compounds from sediment trap experiment off the coast of Peru. In Coastal Upwelling Its Sediment Record. Part A. Response of the Sedimentary Regime to Present Coastal Upwelling (Suess, E., and Thiede, J., eds.), pp. 241-272, Plenum Press, New York. 

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