Phosphorus interface

Phosphorus-containing surfactants are amphiphilic molecules, exhibiting the same surface-active properties as other surfactants. That means that they reduce the surface tension of water and aqueous solutions, are adsorbed at interfaces, form foam, and are able to build micelles in the bulk phase. On account of the many possibilities for alteration of molecular structure, the surface-active properties of phosphorus-containing surfactants cover a wide field of effects. Of main interest are those properties which can only be realized with difficulty or in some cases not at all by other surfactants. Often even quantitative differences are highly useful. 

W. K. Gardner, D. A. Barber, and D. G. Barbery, The acquisition of phosphorus by Liipiniis aibiis L. III. The probable mechanism, by which phosphorus movement in the soil-root interface is enhanced. Plant Soil 70 107 (1983). 

X. L. Li, E. George, and H. Marschner, Phosphorus depletion and pH decrease at the root-soil and hyphae-soil interfaces of VA-mycorrhizal white clover fertilised with ammonium. New Phytologist 119 397 (1991). 

If yellow or red phosphorus is incompletely immersed while undergoing oxidation in hydrogen peroxide solutions, heating at the air-solution interface can ignite the phosphorus and lead to a violent reaction. Such behaviour has been observed with peroxide solutions above 30% (110 vol) concentration. 

Gardner, W.K. Parbery, D.G. Barber, D.A. (1982) The acquisition of phosphorus by Lu-pinus albus L. I. Some characteristics of the soil/root interface. Plant Soil 68 19-32 Garg, A. Matijevic, E. (1988) Preparation and properties of uniform coated colloidal particles. II. Chromium hydrous oxide on hematite. Langmuir 4 38-44 Garg, A. Matijevic, E. (1988) Preparation and properties of uniform coated colloidal parti-... 

Kuo, R.J. Matijevic, E. (1980) Particle adhesion and removal in model systems. III. Monodisperse ferric oxide on steel. J. Colloid Interface Sci. 78 407-421 Kuo, S. Jellum, E.J. (1994) The effect of soil phosphorus buffering capacity on phosphorus extraction by iron oxide-coated paper strips in some acid soils. Soil Sci. 158 124-131... 

Thus, the characteristic topographic function increases continuously from the surface (z = z0) to the lake bottom (z = 0) where it becomes infinitely large. In fact, at the lake bottom a tiny lake volume stays in contact with a finite sediment area. This explains the great spatial and temporal gradients often found close to the bottom of lakes for compounds which are exchanged at the sediment-water interface (oxygen, phosphorus, methane, etc.). 

Assuming a bulk density of 1.05 g/cm3 and a dry weight fraction of 0.1 for the interface sediment, 0.38 mm of sediment would supply the observed 160-m water-column burden of resuspended phases, approximately half the basinwide average annual linear sedimentation. The corresponding amount of sediment was consistent with the mass of allochthonous components in the water column during the March-May spring mixing period (200-300 mg/m3). The quantity of resuspended P was calculated as the product of mass of resuspended sediment (g/m2) and phosphorus concentration in surface sediment (mg of P/g). For a 160-m water column, the amount was 48 mg of P/m2 (25 mg of P/m2 for the mean water-column depth of 85 m). The resuspended P flux (25 mg of P/m2) was also obtained from the product of resuspended Al (mg/m2) and the P Al ratio in bottom sediment. 

The temperature dependence of the linear rate constants for various electron concentrations in phosphorus-doped silicon indicate that the doping has only a slight effect on the associated activation energy. Thus, because B/A is proportional to the rate of the interface reaction, the doping effect is buried in the chemical, electrical, or, possibly, mechanical dependence of surface rate on doping. 

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