Sedimentation, factors affecting

Adsorption — An important physico-chemical phenomenon used in treatment of hazardous wastes or in predicting the behavior of hazardous materials in natural systems is adsorption. Adsorption is the concentration or accumulation of substances at a surface or interface between media. Hazardous materials are often removed from water or air by adsorption onto activated carbon. Adsorption of organic hazardous materials onto soils or sediments is an important factor affecting their mobility in the environment. Adsorption may be predicted by use of a number of equations most commonly relating the concentration of a chemical at the surface or interface to the concentration in air or in solution, at equilibrium. These equations may be solved graphically using laboratory data to plot "isotherms." The most common application of adsorption is for the removal of organic compounds from water by activated carbon. 

Reddy KS, Gambrell RP. 1987. Factors affecting the adsorption of 2,4-D and methyl parathion in soils and sediments. Agric Ecosyst Environ 18 231-241. 

Eggleton J, Thomas KV (2004) A review of factors affecting the release and bioavailability of contaminants during sediment disturbance events. Environ Int 30(7) 973-980... 

Whitfield and McKinley [24] studied some of the factors affecting the determination of particulate carbon and nitrogen in river water sediments. 

Despite these reservations, environmental distribution values may be considered valid for the sorption process, to a first approximation. On this basis, it can be concluded that detected environmental partition coefficients show the clear affinity of surfactants to particulate material. The affinity is higher for cationic surfactants than for other surfactants, as shown by the high partition coefficient values (Table 5.4.1). Partition coefficients are also higher for the water column than for sediments (Table 5.4.1), and it is difficult to offer an explanation for this, bearing in mind the many factors affecting the partition coefficient in both natural water and sediment. 

Socha, S.B. and Carpenter, R. Factors affecting the pore water hydrocarbon concentrations in Puget Sound sediments, Geochim. Cosmochim. Acta, 51(5) 1273-1284,1987. 

The history of the surface is an additional factor affecting the release of contaminants adsorbed on solid phases into the liquid or gaseous phase. For example, the effect of drying on contaminant desorption is influenced by the time allowed for its transport into the aqueous phase. In sorbing systems, like sediments that are permanently wet, the history of the system determines the fate of sorbed molecules (Pignatello 1989). 

Contours like this are qualitatively the same sort of thing we obtain from sedimentation-diffusion experiments as shown in Figure 2.9. Therefore let us consider the relationship between the two types of data. In general, exactly the same factors affect both the intrinsic viscosity and the friction factor ratio, but the functional dependencies are somewhat different. Figure 4.13b shows how a contour of f/f0 selected from a sedimentation-diffusion study and an intrinsic viscosity contour selected on the basis of viscosity experiments might overlap. In this case the solvation-ellipticity combination is characterized unambiguously a/b = 2.5 and (ml b/m2) = 1.0. Figure 4.13b shows the complementarity of viscosity and sedimentation-diffusion data. 

Simulation of Sediment-Water Interactions. To investigate factors affecting the flux of Mn across the sediment-water interface, we in-... 

Klassen, R.A. (2004) Geological factors affecting the distribution of trace metals in glacial sediments of central Newfoundland. Environmental Geology, 33(2-3), 154-69. 

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