Settling particles composition

The ratios Zn/C and Cu/C are given in order to compare the composition of the settling particles in different systems... 

Colombo, J.C., Silverberg, N., and Gearing, J.N. (1996a) Biogeochemistry or organic matter in the Laurentian Trough. I. Composition and vertical fluxes of rapidly settling particles. Mar. Chem. 51, 277-293. 

Table I. Average Composition of Settling Particles in Lake Sempach,...

We will illustrate some of the processes involved in a eutrophic lake. Points of interest are the factors that determine the speciation of copper and zinc, the role of biologically produced ligands, how copper and zinc are bound in the settling particles, and whether the settling particles reflect the composition of algae with respect to trace elements. 

These Zn P and Cu P ratios (or the corresponding Zn C and Cu C ratios) may be compared to those observed in other systems and in algae (Table III). The composition of the settling particles in Lake Zurich is quite similar to that in Lake Greifen this similarity is reflected in these ratios. 

Table I. Composition of the Settling Particles Collected in Lake Creifen...

A flow field is laminar, when it is governed by the viscous properties. That applies to very slow fluid velocities or very high viscosities, which are typical for polymer composites or highly concentrated suspensions (e.g. paints). There are three ideal types of laminar flow uniform flow (e.g. experienced by settling particles), shear flow (e. g in rheometers or pipes), and elongational flow (e.g. in nozzles and diffusers). Only the latter two are relevant for deagglomeration. 

There have been only a few studies of the lanthanide composition of particles in the oceans. We will distinguish suspended particles collected in bottles from settling particles collected in sediment traps. Sediment trap data have been reported by Murphy and Dy-mond (1984), Masuzawa and Koyama (1989) and Fowler et al. (1992). Suspended-particle compositions have been reported for anoxic basins by De Baar et al. (1988) and German and Elderfield (1989, 1990). The only data for oceanic suspended particles are those of Bertram and Elderfield (1993) for the Indian Ocean and Sholkovitz et al. (1994) and Jeandel et al. (1995) for the Sargasso Sea (N. Atlantic). The latter study only measured Nd concentrations on suspended and trapped particles. A fuller discussion of the results and interpretations of particle studies is by Sholkovitz et al. (1994). A brief overview follows. 

In the wet process the clay minerals are crushed and slurried with water to allow pebbles and other rock particles to settle out. The limestone is also crushed and slurried. Both materials are stored in separate bins and analyzed. Once the desired ultimate composition is determined, the slurry blend is ground and then partially dried out. 

Finely-ground composition, particles preferably of laminar shape to prevent settling when the enamel is molten. 

The flow problems considered in previous chapters are concerned with homogeneous fluids, either single phases or suspensions of fine particles whose settling velocities are sufficiently low for the solids to be completely suspended in the fluid. Consideration is now given to the far more complex problem of the flow of multiphase systems in which the composition of the mixture may vary over the cross-section of the pipe or channel furthermore, the components may be moving at different velocities to give rise to the phenomenon of slip between the phases. 

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