Clay and Soil

Silicon w is first isolated and described as an element in 1824 by Jdns Jacob Berzelius, a Swedish chemist. Silicon does not occur uncombined in nature, i.e.- as an element. It is found in practically aU rocks as well as in sand, clays, and soils, combined either with oxygen as silica (Si02= silicon dioxide) or with oxygen plus other elements (e.g., aliuninum, mcignesium, calcium, sodium, potassium, or iron) as silicates. Its compounds also occur in all natural waters, in the atmosphere (as siliceous dust), in many plants, and in the skeletons, tissues, and body fluids of some animals. 

Lee, D.Y., Farmer, W.J., and Aochi, Y. Sorption of napropamide on clay and soil in the presence of dissolved organic matter,... 

Competitive adsorption on clay and soils surfaces between a heavy metal contaminant (Cu) and a cationic herbicide (chlordimeform) was reported by Maqueda... 

Bewick M.W. (1979). The adsorption and release of tylosin by clays and soils. Plant and 51 363-370. 

The BioTrol soil washing system is a patented, water-based volume reduction process used to treat excavated soil. It separates slightly contaminated, coarse, washed soil particles from heavily contaminated fine soil particles. The process operates on the premise that (1) contaminants tend to be concentrated in the fine size fraction of soil (sUt, clay, and soil organic matter) and (2) contaminants associated with the coarse soil fraction (sand and gravel) are primarily surficial. The BioTrol soil washing system can be used to treat soils contaminated with petroleum hydrocarbons, pesticides, polychlorinated biphenyls (PCBs), various industrial chemicals, and metals. 

This technology is designed to treat clays soils, nonstratified soils, soils containing more than 50% silt or clay, and soils with hydraulic conductivities of less than 0.001 cm/sec. 

Busenberg, E. and Clemency, C.V., 1973. Determination of the Cation Exchange Capacity of clays and soils using an ammonia electrode. Clays, Clay Miner, 21, 213. 

Figure 2.24. Removal of 14C-2,4-dichlorophenol by laccase immobilized on clays and soil. Reprinted from Ruggiero, P., Sarkar, J. M., and Bollag, J.-M. (1989). Detoxification of 2,4-dichlorophenol by a laccase immobihzed on soil and clay. Soil Sci. 147, 361-370, with permission from Lippincott Williams Wilkins.

Aluminum, a silver-white, malleable, and ductile metal, is the most abundant metallic element in the lithosphere, comprising about 8% of the earth s crust. It is never found free in nature, but occurs combined with other elements, most commonly as aluminosilicates, oxides, and hydroxides in rock, minerals, clays, and soil. It is also present in air, water, and many foods. Bauxite, a weathered rock consisting primarily of aluminum hydroxide minerals, is the primary ore used in aluminum production. Aluminum enters environmental media naturally through the weathering of rocks and minerals. Anthropogenic releases are in the form of air emissions, waste water effluents, and solid waste primarily associated with industrial processes, such as aluminum production. Because of its prominence as a major constituent of the earth s crust, natural weathering processes far exceed the contribution of releases to air, water, and land associated with human activities. 

There appears to be some relation between composition and mode of origin but with the present data, it is difficult to deduce. In general, the high-Mg, low-Al montmorillonites are most likely to have formed by the alteration of volcanic material and the high-Al beidellite type, to have been of hydrothermal origin or to have been formed as gouge clay and soil clay. In the soil clays much of the excess A1 is present as hydroxyl A1 in the interlayer position. 

Sumner, M.E., 1963. Effect of iron oxides on positive and negative charges in clays and soils. Clay Miner., 5 218-224. 

Ternary cation exchange, 216 Tetrahedral coordination, 102 Titration curves, 27-29, 154-159 Equivalence points, 28-29 pH-bufifering, 86-88 Acid clays and soils, 154-160 Total dissolved solids (TDS), 479, 491 Toxicity, 484 Indicators, 484 Ceriodaphnia, 484 Water fleas, 484 TIEs, 484 Metals, 484 Hard- metals, 12 Soft-metals, 12 Triazines, 345, 357 Trioctahedral silicates, 121... 

Values of and n for some exchange reactions on ferric oxide, montmorillonite clays, and soils are given in Table 10.8. Example plots of Eq. (10.26) for Cd and Pb +exchange onto calcium montmorillonite are shown in Fig. 10.15. The plots show that as the concentrations of Cd and Pb " decrease below those of Ca, values drop below unity. This indicates that the montmorillonite... 

Fendorf, S. E. (1999). Fundamental aspects and applications of x-ray absorption spectroscopy in clay and soil science. In Synchrotron X-ray Methods in Clay Science, Vol. 9, ed. Schulze, D. G., et al., CMS Workshop Lectures, Clay Minerals Society, Boulder, CO, 20-67. 

Moliner AM, Street JJ. 1989b. Interactions of hydrazine with clays and soils. J Environ Qual 18 487-491. 

Talibudeen, O. (1984), Change Heterogenity and the Calorimentry of K—Ca Exchange-Adsorption in Clays and Soils, Adsorpt. Sci. Tehcnol. 1, 235-246. 

The migration of explosives from surface soil to the water table is governed by their physicochemical properties and the mechanisms of their interaction with the soil matrix (mainly clay, and soil organic matter). The frequent detection of TNT (S = 140 mg/L) and RDX (S = 45 mg/L) in groundwater of contaminated sites is confirmed. As for HMX, its limited solubility in water (<5 mg/L) restricts its presence close to the soil surface. No field data is yet available on CL-20. 

Thermoluminescent dating (TL). This technique is useful for dating pottery and ceramics (Wagner et al, 1983). It is based on the cumulative effect of radiation from disintegrating radioactive isotopes present in minerals of most rocks, clays and soils. The ionizing radiation may cause electrons to detach from their parent atom and become trapped in lattice defects of the material. As the material ages, defects accumulate. When a ceramic object is fired, trapped electrons are freed and, since radioactive minerals are incorporated in the object, defects start to accumulate again. 

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