Resuspension

This definition of the resuspension factor, kr, implies an equilibrium relationship between the two quantities which may be achieved only over an extensive area of uniform deposition. In principle, when the deposition varies spatially, resuspension would be better predicted by us ing the resuspension rate, A in s which is defined as the ratio of vertical flux (Bq m and the radioactivity deposited on the ground (Bqm )  

the resuspension rate A is the fraction removed per second by resuspension process. The use of this quantity with a suitable dispersion and deposition model would enable the movement of a radioactive nuclide from place to place to be predicted. Such an approach is necessary for estimating the radionuclide concentration in air due to resuspension downwind of an area heavily affected by the deposition process. Whether kr or A is used, it is clear that the value of the parameter must be expected to vary with many environmental variables. The most important of these environmental variables will be time after deposition, surface structure, nature of the radioactivity, wind speed, surface moisture and rate of mechanical disturbance of the surface. 

A simple exponential function for the resuspension factor, kr, gives a reasonable description of the decrease with time (Garland and Pattenden, 1989) as follows  

PCBs that have historically accumulated in the sediments may return to the water through resuspension-desorption and through continuous diffusion from sediment porewaters. 

It is possible that resuspension of PCBs during major storms may be as large a source as the tributaries. However, the fate of the resuspended contaminants is unclear. The EEGLE study found that most of the resuspended 

Diffusion of PCBs from highly contaminated surficial sediments in areas of concern may be an important net source to the Great Lakes. In fact, PCB diffusion from the porewaters of heavily contaminated coastal and riverine sediments may justify the removal of those sediments. Porewater diffusion in open lake sediments is not a major source. Diffusion of PCBs from porewater is governed by an effective diffusion or mass transfer coefficient and the 

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Important intermedia transfer mechanisms affecting soil contaminants include volatilization or resuspension to the atmosphere and biouptake by plants and soil organisms. These, in turn, introduce contaminants into the food chain. 

Replacement in kind - A replacement that satisfies design specifications, resuspension - Re-entrainment of particulate into a wind field for dispersion. 

BCG Cultures of live BCG cells in liquid or on solid media 1 Bacteria centrifuged from medium 2 Resuspension in stabilizer 3 Freeze-drying Viable count induction of sensitivity to tuberculin in guinea-pigs Exclusion of virulent mycobacteria absence of excessive dermal reactivity... 

Typhoidt whole cell Cultures of Sat. typhi grown in liquid media 1 Killing with heat or phenol 2 Separation and resuspension of bacteria in saline Induction of antibodies in rabbits Exclusion of live Sai. typhi... 

Our standard incorporation assays contained resuspended particulate enzyme, labelled UDP-Gal (0.1 mM) and (10 mM) in resuspension buffer (Tris, pH 7.5). After incubation, reaction mixtures were heated briefly to 100°C and soluble lupin galactan was added, to ensure the precipitation of small amounts of galactan formed in the en me reaction and dissolved during the heating step. Precipitation of macromolecular products was achieved by adding methanol to a final concentration of 70%. The pellet was freed of soluble labelled products, including residual UDP-Gal, by repeated extraction with hot 70% methanol and was then analysed for labelled (l- )-P-D-galactan. The supernatant was analysed for soluble labelled products. 

Removal to sediments. Removal of surface-reactive trace elements from the oceans readily occurs by adsorption onto settling particles, and this process is most pronounced in the typically high-energy, particle-rich estuarine environment. Particles are supplied by rivers, augmented by additions of organic material generated within the estuary. Also, floes are created in estuaries from such components as humic acids and Fe. The interaction between dissolved and colloidal species is enhanced by the continuous resuspension of sediments in... 

Baskaran and Santschi (1993) examined " Th from six shallow Texas estuaries. They found dissolved residence times ranged from 0.08 to 4.9 days and the total residence time ranged from 0.9 and 7.8 days. They found the Th dissolved and total water column residence times were much shorter in the summer. This was attributed to the more energetic particle resuspension rates during the summer sampling. They also observed an inverse relation between distribution coefficients and particle concentrations, implying that kinetic factors control Th distribution. Baskaran et al. (1993) and Baskaran and Santschi (2002) showed that the residence time of colloidal and particulate " Th residence time in the coastal waters are considerably lower (1.4 days) than those in the surface waters in the shelf and open ocean (9.1 days) of the Western Arctic Ocean (Baskaran et al. 2003). Based on the mass concentrations of colloidal and particulate matter, it was concluded that only a small portion of the colloidal " Th actively participates in Arctic Th cycling (Baskaran et al. 2003). 

Am levels reflect resuspension of dust contamination at the WIPP site and not background 241Am levels. Present background levels result from past atmospheric nuclear testing and would be fairly uniform throughout the northern hemisphere. 

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