Migration vertical

The modeling of a groundwater chemical pollution problem may be one-, two-, or tlu-cc-dimcnsional. The proper approach is dependent on the problem context. For c.xamplc, tlie vertical migration of a chemical from a surface source to the water table is generally treated as a one-dimensional problem. Within an aquifer, this type of analysis may be valid if the chemical nipidly penetrates the aquifer so that concentrations are uniform vertically and laterally. This is likely to be the case when the vertical and latcrtil dimensions of the aquifer arc small relative to the longitudinal scale of the problem or when the source fully penetrates the aquifer and forms a strip source. 

Vertical Migration. Historically, surface samples at other TCDD sites have been taken to depths of 0 to 6 inches using picks and... 

Additional sampling is needed to fully characterize the vertical migration of TCDD In those areas contaminated by dispersion. 

May affect natural groundwater flow gradients at a site, potentially resulting in lateral or vertical migration of the contaminant plume... 

Van Duyn-Henderson, J. and D.C. Lasenby. 1986. Zinc and cadmium transport by the vertically migrating opossum shrimp, Mysis relicta. Canad. Jour. Fish. Aquat. Sci. 43 1726-1732. 

Table 32.12 Time Required to Transport Selected Radionuclides Added into Marine Waters at Surface out of the Upper Mixed Layer by Biological Transport (Processes include diurnal vertical migration, fecal pellets, and sinking of dead matter.)...

Bebout BM, Garcia-Pichel F (1995) UV-B induced vertical migrations of cyanobacteria in a microbial mat. Appl Environ Microbiol 61 4215 4222... 

Subsurface organisms and organic residues also may affect vertical migration of contaminants. In a laboratory experiment by Tengen et al. (1991), the influence of microbial activity on the migration of Cs+ and the effect of organic matter residue on Cs+ retention were illustrated. These experiments were performed to understand... 

Goldberg, I.S. 1998. Vertical migration of elements from mineral deposits. Journal of Geochemical Exploration, 61, 191-202. 

Fig. 21. Schematic representation of the molecular weight dependence of rapid transport involving structured flows as vehicles for the transport. Large molecules are retained in vertically migrating rapid flows and undergo only slight or no lateral diffusion. Small molecules, on the other hand, are not retained in rapidly moving vertical flows but diffuse laterally into a vertical flow migrating into the opposite direction...

Most of the features of the theoretical treatment of bubble motion are present in the treatment that considers the water incompressible and neglects gravity effects. We quote from Cole (Ref 1, Chapt 8) The simplest approximation to the true motion of the bas bubble is the one in which it is assumed that the motion of the surrounding water is entirely radial and there is no vertical migration. In this approximation, which has been discussed by a number of writers, the hydrostatic buoyance resulting from differences in hydrostatic pressure at different depths is neglected. It is thus assumed that at an infinite distance from the bubble in any direction the pressure has the same value as the initial hydrostatic pressure P0 at the depth of the charge... 

A variety of factors affect the horizontal and vertical migration of PAHs, including contaminant volume and viscosity, temperature, land contour, plant cover, and soil composition (Morgan Watkinson, 1989)- Vertical movement occurs as a multiphase flow that will be controlled by soil chemistry and structure, pore size, and water content. For example, non-reactive small molecules (i.e., not PAHs) penetrate very rapidly through dry soils and migration is faster in clays than in loams due to the increased porosity of the clays. Once intercalated, however, sorbed PAHs are essentially immobilized. Mobility of oily hydrophobic substances can potentially be enhanced by the biosurfactant-production capability of bacteria (Zajic et al., 1974) but clear demonstrations of this effect are rare. This is discussed below in more detail (see Section 5 5). 

Shook, G.M., Kostarelos, K., and Pope, G.A. (1997). Minimization of vertical migration of DNAPLs using surfactant enhanced aquifer remediation at neutral buoyancy. Presented at SPE Annual Tech. Conf., Soc. Petrol. Eng., 39294, 1-8. 

Siebenaller, J.E (1984). Analysis of the biochemical consequences of ontogenetic vertical migration in a deep-living teleost fish. Physiological Zoology 57,598-608. 

Zusser, S.G. (1971). Diurnal Vertical Migrations of Fish (In Russian). Pishchevaya Promyshlennost, Moscow, 224 pp. 

As seen from (3.29), zooplankton are considered passive elements of the ecosystem subject to physical processes of transference in space as a result of water movement. However, zooplankton are known to migrate mainly in the vertical direction. In the given model we can use a simple mechanism to simulate the process of vertical migration of zooplankton. For this purpose, we divide the whole water thickness into two layers 0 < z < z0 and z0 < z < H. Let us suppose that zooplank-... 

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