Fixation by clay minerals

Eberl, D. D. 1980. Alkali cation selectivity and fixation by clay minerals. Clays Clay Miner. 28 161-172. 

Inoue, a. 1983. Potassium fixation by clay-minerals during hydrothermal treatment. Clays and Clay Minerals, 31(2), 81-91. 

Figure 3. The general nitrogen model for illustrating the bio geochemical cycling in Forest ecosystems. Explanations for the fluxes 1, ammonia volatilization 2, forest fertilization 3, N2-fixation 4, denitrification 5, nitrate respiration 6, nitrification 7, immobilization 8, mineralization 9, assimilatory and dissimilatory nitrate reduction to ammonium 10, leaching 11, plant uptake 12, deposition N input 13, residue composition, exudation 14, soil erosion 15, ammonium fixation and release by clay minerals 16, biomass combustion 17, forest harvesting 18, litterfall (Bashkin, 2002).

Sawhney, B. L., "Sorption and Fixation of Microquantities of Cesium by Clay Minerals Effect of Saturating Cations,"... 

Hamdy, A. A. and G. Gissel-Nielsen. 1977. Fixation of selenium by clay minerals and iron oxides. Z. Pflanzenemaehr. Bodenkd. 140 63—70,... 

Sawhney, B. L. 1972. Selective sorption and fixation of cations by clay minerals A review. Clays Clay Miner. 20 93-100. 

Reddy MR, Perkins HF. 1976. Fixation of manganese by clay minerals. Soil Science 121 21-24. 

Phosphates are fixed by Fe-hydroxides and together with these by clay minerals. In tropical soils, phosphorus fixing on Fe-com-pounds is widespread. Phosphate fixation is appreciable in soils rich in allophane, derived from volcanic rocks. 

Fixation of difficultly-exchangeable ammonium by clay minerals is limited to the 2 1 type minerals. For information on the structure of clay minerals reference should be made to Hendricks (1945) Ross and Hendricks (1945) Gieseking (1949) Grim (1953) ... 

The cations that may be fixed by clay minerals include Rb and Cs in addition to NH4 and K (Joffe and Levine, 1947). Presumably they are all competitive although Uttle work has been reported with Rb and Cs". In the case of and NH4 it is well established (Bower, 1950) that the addition of either to soil will reduce the fixation of the other added subsequently, and the reduction is nearly proportional to the amount added. This is also shown by the work of Stanford and Pierre (1947). Their work was with a soil in which montmorillonite was the predominant mineral but simular results have been obtained with vermicuhte. The behavior of the ions differs somewhat with concentration, time of contact, and type of clay but these variables are usually of minor importance. 

Total radiocesium-137 deposited in soils at Chernobyl sites 2-15 km from the reactor was estimated at 1,660,000 Bq/m, mainly as insoluble fuel particles. The half-time persistence of Cs in surface soils 0-2 cm in depth decreased from 9 years in 1987 to 3 years in 1994 but the residence time of this isotope increased with increasing depth over time. This increase in deeper layers is attributed to the progressive fixation of radiocesium by clay minerals of the soil. 

One such model is that formulated in 1979 by van Veen and Frissel and shown in general outline in figure 4. This scheme shows transformation processes which are a composite of separate sub-models, namely, mineralization and immobilization, nitrification, denitrification, ammonia volatilization, fixation on clay minerals, and leaching. Components... 

Richahds, G. E., and E. O. McLean, 1963. Potassium fixation and release by clay minerals and soil clays on wetting and drying. Soil Sci. 95 308. 

Sorption and fixation of microquantities of Cs by clay minerals effect of saturating... 

Beek and Frissel (1973) Growth of nitrifier and ammonifer bacteria by Michaelis-Menten kinetics NH4 oxidation by first-order kinetics with environmental variables mineralization of proteins, sugars, cellulose, lignin, and living biomass by first-order kinetics immobilization by first-order kinetics including considerations for microbial biomass and C/N ratio NH3 volatilization by diffusion NH4 clay fixation by equilibrium model. 

Weaver, C. E., 1958. The effects and geologic significance of potassium fixation" by expandable clay minerals derived from muscovite, biotite, chlorite, and volcanic material. Am. Mineralogist, 43 839-861. 

Although many soil scientists had considered the possible mechanisms which soils employ for the retention [fixation] of phosphorus, it remained for Haseman et al. (1950) to demonstrate that phosphorus could — and in experimental situations did — replace the silicon of micas and clay minerals in order to form crystalline hydrous aluminium phosphates of sodium, ammonium and potassium. Prior to experimentation by this group, associated with the laboratories of the Tennessee Valley Authority (TVA), most authors attributed the retention of phosphorus by soils to combination with calcium to produce fairly insoluble minerals to adsorptive, exchangeable combination with silicate minerals and to formation of phosphates of iron... 

Eberl, D. D., J. Srodon, and H. R. Northrop (1986). Potassium fixation in smectite by wetting and drying. In "Geological Processes at Mineral Surfaces" (J. A. Davis and K. F. Hayes, eds.). Series No. 323, pp. 296-325. American Chemical Society, Washington, D.C. Eggleton, R. A. and P. R. Buseck (1980). High resolution electron microscopy of feldspar weathering. Clays and Clay Minerals 28, 173-178. 

One of the factors which has confused mechanism analysis has been the failure to make a distinction between studies involving micro- and macro-concentrations of the heavy metals. Whereas, with micro-concentrations, sorption reactions may predominate, precipitation frequently occurs with macro-concentrations (68). Exchange of copper and zinc with hydrogen on clay mineral surfaces was proposed as a cause of zinc and copper fixation in soils by DeMumbrum and Jackson (59) who noted... 

During decomposition most of the nitrogen is immobilized initially, at least, in microbial cells, which in turn are broken down. In the process, a considerable portion of the nitrogen reacts with phenols, quinones, and other ring compounds derived from lignin, or synthesized by microorganisms, to form humic substances, some of which are heterocyclic. Amino acids and ammonia are subject to such chemical reactions, that may be catalyzed by microbial enzymes. In soils with 2 1 clay minerals any ammonia that is formed is also subject to fixation in the clay lattice (see Chapter 8 and 11). 

R. L. Parfitt, J. D. Russell, and V. C. Farmer, Confirmation of the surface structures of goethite (a-FeOOH) and phosphated goethite by infrared spectroscopy, J.C.S. Faraday I 72 1082 (1976). R. L. Parfitt, Phosphate adsorption on an oxisol. Soil Sci. Soc. Am. J. 41 1065 (1977). R. L. Parfitt, R. J. Atkinson, and R. St. C. Smart, The mechanism of phosphate fixation on iron oxides. Soil Sci. Soc. Am. J. 39 837 (1975). R. L. Parfitt, The nature of the phosphate-goethite (a-FeOOH) complex formed with Ca(H2P04)2 at different surface coverage. Soil Sci. Soc. Am. J. 43 623 (1979). J. B. Harrison and V. E. Berkheiser, Anion interactions with freshly prepared hydrous iron oxides. Clays and Clay Minerals 30 97 (1982). 

Studies since the 1960s have shown that Cs is sorbed very selectively by micaceous clay minerals, particularly illite, a process which is believed to be analogous to the fixation of potassium in the clay interlayer structures (e.g. 6,7). The more recent work by Cremers and co-workers (8) has enabled a quantitative characterisation of the Cs-selective sorption sites in soils and sediments, which are believed to be located on the frayed edges of illite (the frayed edge sites or FES). These authors have shown that the interaction of cesium with sediment and soil particles can be described more mechanistically in terms of an ion exchange process ... 

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