Minerals and Soils

Fluoride (F) is ubiquitous. It occurs naturally in the atmosphere through volcanic eruption and in the earth s crust. It rarely occurs freely in nature but combines with a variety of elements to form fluorides that exist in minute amounts in air, water, minerals and soils, vegetation, and body tissues. 

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In addition to its presence as the free element in the atmosphere and dissolved in surface waters, oxygen occurs in combined form both as water, and a constituent of most rocks, minerals, and soils. The estimated abundance of oxygen in the crustal rocks of the earth is 455 000 ppm (i.e. 45.5% by weight) see silicates, p. 347 aluminosilicates, p. 347 carbonates, p. 109 phosphates, p. 475, etc. 

Goldberg S., Forster H.S., Heick E.L. Boron adsorption mechanisms on oxides, clay minerals and soils inferred from ionic strength effects. Soil Sci Soc Am J 1993 57 704-708. 

Sorption and Desorption of Arsenic by Soil Minerals and Soils in the Presence of Nutrients and Organics... 

The effect of other inorganic anions (sulfate, molybdate, silicate), low molecular mass organic ligands (LMMOLs, such as oxalate, malate, citrate, tartrate and succinate), and fulvic or humic acid on the sorption of arsenate and arsenite onto variable charge minerals and soils has been studied (Roy et al. 1986 Grafe et al. 2001 Liu et al. 2001 Violante et al. 2005a,b). 

Soil microbes. Effects include reduced microbial biomass and/or species diversity, thus affecting microbial processes such as enzyme synthesis and activity, litter decomposition, associated with carbon and nitrogen mineralization, and soil respiration ... 

Potassium-Calcium Exchange Equilibria in Aluminosilicate Minerals and Soils... 

Hendershot,W.H. Lavkulich, L.M. (1983) Effect of sesquioxide coatings on surface charge of standard mineral and soil samples. Soil Sci. Soc. Am. J. 47 1252-1260... 

Murad, E. (1990) Application of Fe Mossbauer spectroscopy to problems in clay minerals and soil science possibilities and limitations. Adv. Soil Sci. 12 125-157... 

Davies, J. E. D., and Jabeen, N. (2002). The adsorption of herbicides and pesticides on clay minerals and soils. Part 1. Isoproturon. J. Inclusion Phenom. Macrocyclic Chem. 43(3 4), 329-336. 

Sparks and Jardine (1984) found that the first-order equation best described potassium adsorption kinetics on clay minerals and soils. However, Havlin and Westfall (1985) reported that the power-function equation described nonexchangeable potassium release kinetics better than first-order or a number of other models. 

Sparks, D. L. (1965). Kinetics of ionic reactions in clay minerals and soils. Adv. Agron. 38, 231-266. 

Ogwada, R. A., and Sparks, D. L. (1986c), Kinetics of ion exchange on clay minerals and soil. II. Elucidation of rate-limiting steps. Soil Sci. Soc. Am. J. 50, 1162-1164. 

The first comprehensive study of fluoride adsorption onto minerals and soils was published in 1967 [57], Since that time, several workers have investigated the adsorption of fluoride on various substrates. These studies include the use of Ando soils of Kenya [58], Illinois soils of USA [59], Alberta soil Luther [60], il-lite-goethite soils in China [2] clay pottery [61,62], fired clay [63], fired clay chips in Ethiopia [12], kaolinite [64], bentonite and kaolinite [65,66] and fly ash [17],... 

Figure 9.15. Relationship between critical salt concentrations for reference clay minerals and soil clays in mixed-ion systems (raw data were taken from Arora and Coleman, 1979).

TABLE 9.4. Influence of pH on the Critical Salt Concentration (NaHCOj) of Reference Clay Minerals and Soil Clays... 

Admixes to the soil in stabilization process compound with the minerals and soil grains, and may lead to generation of new chemical mix with different properties in comparison with the primary properties of soil. Lime as an ordinary stabilizer compounds with soil in the form of quick-lime (CaO) or hydrated lime (Ca(OH)2) can improve soil physical properties [7]. 

A more direct approach to study EM weathering is the use of tracer elements as used by Blum et al. (2002). They examined calcium uptake by different tree species in the Hubbert Brook Experimental Forest in northeastern USA. They used the fact that the different calcium sources (atmospheric deposition, calcium silicate weathering and apatite weathering) have different Ca/Sr ratios. In the ecosystem, strontium is believed to behave in a similar fashion as calcium (Aberg et al., 1990). Atmospheric deposition, calcium silicate minerals and soil water have similar Ca/Sr ratios (120-300), but apatite has a much higher Ca/Sr ratio (2200-2920). 

Fig. 13.3. The range of Ca/Sr ratios (w/w) as measured in the leaves of five different tree species and a fern, in different minerals and soil water in a mixed forest ecosystem of north-eastern USA. (Modified from Blum et al, 2002.) Atm. dep., atmospheric depression.

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