Mineral components, soil

The inorganic component of soil is dominated by four elements O, Si, Al, and Fe (Jackson, 1964). Together with Mg, Ca, Na, and K they constitute 99% of the soil mineral matter (see Table 8-2). Minerals in soil are divided into primary and secondary minerals. Primary minerals, which occur in igneous, metamorphic, and sedimentary rocks, are inherited by soil... 

Xenobiotics exist not only in the free state but also in association with organic and mineral components of particles in the water mass, and the soil and sediment phases. This association is a central determinant of the persistence of xenobiotics in the environment, since the extent to which the reactions are reversible is generally unknown. Such residues may therefore be inaccessible to microbial attack and apparently persistent. This is a critical factor in determining the effectiveness of bioremediation (Harkness et al. 1993). Although the most persuasive evidence for the significance of reduced bioavailability comes from data on the persistence of agrochemicals in terrestrial systems (Calderbank 1989), the principles can be translated with modification to aquatic and sediment phases that contain organic matter that resembles structurally that of soils. 

In practice, evaluating the wettability of a soil is far more uncertain, because soil is a mixture of gravel, sand, silt, and clay particles, as well as other chemical precipitates. The mineral components of soil particles include quartz, feldspar, carbonates, and clay. These components have different wettability by water and oil. Therefore, the retention of oil or water in a soil matrix is heterogeneous and variable. The general wettability of soil or liquid retention in a soil is reported on a statistical basis. 

The enzymatic activity in soil is mainly of microbial origin, being derived from intracellular, cell-associated or free enzymes. Only enzymatic activity of ecto-enzymes and free enzymes is used for determination of the diversity of enzyme patterns in soil extracts. Enzymes are the direct mediators for biological catabolism of soil organic and mineral components. Thus, these catalysts provide a meaningful assessment of reaction rates for important soil processes. Enzyme activities can be measured as in situ substrate transformation rates or as potential rates if the focus is more qualitative. Enzyme activities are usually determined by a dye reaction followed by a spectrophotometric measurement. 

Along with this were investigations of the elemental content of plants and the relationship between those elements found in soil and those found in plants. As these investigations advanced, it became evident that the inorganic components in soil were essential to plant growth and that crop production could be increased by increasing certain mineral components in soil. It did not take too long to determine that ammonia, phosphorous, and potassium are the three essential components that increase plant productivity. At this early point,... 

Since sorption is primarily a surface phenomenon, its activity is a direct function of the surface area of the solid as well as the electrical forces active on that surface. Most organic chemicals are nonionic and therefore associate more readily with organic rather than with mineral particles in soils. Dispersed organic carbon found in soils has a very high surface-to-volume ratio. A small percentage of organic carbon can have a larger adsorptive capacity than the total of the mineral components. 

Metal Ion Adsorption in Mixtures of Multiple Solid Phases. One of the arguments put forth for extending the concepts of solution coordination chemistry to heterogeneous systems is the hypothesis that the mineral components of soils or sediments can be considered as ligands which compete for complexation of adsorbates. To this end, it is important to know the relative ability of different mineral surfaces to complex solutes. 

The scheme proposed above requires microbial colonization of the material and excludes degradation by amylases and cellulases that are present in soils (28), but are not newly synthesized or associated with microbial cells. Active polysaccharide hydrolases are found in nearly all soils, but these enzymes are primarily bound to soil organic matter or mineral components attachment is firm enough to severely limit migration of the enzymes from surrounding soil to the film. 

Approximately 40 to 50% of the total amount of phenolics sorbed was retained by the organic matter fraction (27). In surface soil layers, organic matter is frequently intimately associated with the mineral components present, providing a large surface area and reactive sites for surface interaction. Soil acidity has a major influence on phenolic adsorption by the organic carbon fraction, since the degree of dissociation of the phenolic acids is pH-dependent. Whitehead and coworkers (28) observed that the extractability of several phenolic acids was highly dependent upon the extractant pH between pH 6 and 14. The amount extractable continually increased with extractant pH thus the extracted acids could not be readily classified into distinct fractions. 

Detritivores reduce size, increase surface and mix soil enhance conta with mineral components... 

In its inorganic form, P is a nutrient showing low solubility and mobility in the soil, because it easily reacts with the soil mineral components (clay, iron and aluminum oxides, and carbonates) (Stevenson, 1986). The P content in humic substances ranges from 0.1% to 1.0% and is particularly abundant in humic acids. By using 31P NMR, it was shown that different forms of P can be associated with humic fractions... 

It is necessary to understand the behavior of soil-water and its mineral components (e.g., nutrients, con taminants) for the purpose of developing conceptual and/or mechanistic process models. Such models can be used to predict nutrient fate in soil-water or contamination-decontamination of soil-water and to develop soil-water remediation-decontamination technologies. To gain an understanding of the soil-water mineral components, their physical and chemical properties need to be known. 

The components of soils and rocks have different size, shape, and quality. The particle size of organic components usually is in the colloid range (<500 nm) mineral components have different dispersity. The first classification system of soils on the basis of particle size was done by Atterberg (1905). Practically, this classification has been used until now, though some countries have their own classifications, considering their widespread soil types. The size of soil particles will also determine how the soil fraction is named (e.g., clay, sand, silt, rock, etc.). Table 1.6 provides these names along with the standard diameter of the particles for the international classification system. 

In this chapter, the relationship of geological origins and interfacial properties of bentonite clay will be reviewed first. Then we will discuss the migration of water-soluble substances in rocks and soil, and the effect of sorption on the migration. A linear model will be derived by which the quantity of ion sorbed on rocks can be estimated when the mineral composition and sorption parameters of the mineral components are known. Surface acid-base properties of soils will be discussed, and the sorption of an anion (cyanide ion) will be shown on different soils and sediments. 

Exchangeable acidity includes exchangeable Al3+ as well as exchangeable H+ on the permanent charges of mineral components. Usually, there is a small amount of acid mineral soils, but it is more abundant in organic soils. It can be extracted with neutral salt solutions such as KC1, CaCl2, or NaCl (Sevink et al. 1998). 

The results show that the sorption of cyanide on soils and sediments is fast it reaches equilibrium within 10 minutes. The sorbed quantity, however, is low. From 10 4-10 3 mol/dm3 cyanide solutions, it is about 10 7 mol/g. This means an approximately 10-3 dm3/g distribution ratio for cyanide ion. This value is typical for the anion sorption of soils, and it is explained by the interfacial properties of soil components. The main mineral components of soils (primary silicates, clay minerals, oxides) have negative surface charges at pH applied (about 8.5), inhibiting the... 

The nature of the parent material is the most important factor influencing the mineral components of a soil. In particular, the textural (particle size) properties and inherent fertility are directly affected by the types of rocks and minerals found in the parent material. 

Labeling of plants via a nutrient solution is more efficient than by soil application due to the possible adherence of the added mineral on soil components. Stem injection may be an efficient labeling technique, but until the mineral complexes which are transported in the vascular system are clearly defined, this technique may not result in deposition of isotopes which are characteristic of field grown crops. 

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