Soils particle sizes

TABLE 52 Soil Particle Size and Soil Types... 

Adult subjects who ingested soil (particle size less than 250 im) from the Bunker Hill NPL site absorbed 26% of the resulting 250 pg/70 kg body weight lead dose when the soil was ingested in the fasted state and 2.5% when the same soil lead dose was ingested with a meal (Maddaloni et al. 1998). There are no reported measurements of the absorption of soil-bome lead in infants or children. Additional evidence for a lower absorption of soil-bome lead compared to dissolved lead is provided from studies in laboratory animal models. In immature swine that received oral doses of soil from one of four NPL sites (75 or 225 ig Pb/kg body weight), bioavailability of soil-bome lead ranged from 50% to 82% of that of a similar... 

Sessitsch A, Weilharter A, Gerzabek MH, Kirchmann H, Kandeler E (2001) Microbial population structures in soil particle size fractions of a long-term fertilizer field experiment. Appl Environ Microbiol 67 4215-4224... 

Schmidt, M., Knicker, H., Hatcher, P., and Kogel-Knabner, I. (1997a). Improvement of 13C and 15N CPMAS NMR spectra of bulk soils, particle size fractions and organic material by treatment with 10% hydrofluoric acid. Eur. J. Soil Sci. 48,319-328. 

Soils exhibit a large variety of characteristics that are used to classify them for various purposes, including crop production, road construction, and waste disposal. The parent rocks from which soils are formed obviously play a strong role in determining the composition of soils. Other soil characteristics include strength, workability, soil particle size, permeability, and degree of maturity. 

Table 7-12. Rainsplash of soil onto tomato plants after 4 consecutive storms as a function of soil particle size fraction and height above ground surface (Dreicer et al., 1984).

Ljung, K., Selinus, O., Otabbong, E., andBerglund, M. (2006). Metal and arsenic distribution in soil particle sizes relevant to soil ingestion by children. Appl. Geochem. 21, 1613—1624. 

The mobility of uranium in soil and its vertical transport (leaching) to groundwater depend on properties of the soil such as pH, oxidation-reduction potential, concentration of complexing anions, porosity of the soil, soil particle size, and sorption properties, as well as the amount of water available (Allard et al. 

Cheshire M. V. and Mundie C. M. (1981) The distribution of labelled sugars in soil particle size fractions as a means of distinguishing plant and microbial carbohydrate residue. J. Soil Sci. 32, 605 -618. 

Christensen B. T. and Sprensen L. H. (1985) The distribution of native and labelled carbon between soil particle size fractions isolated from long-term incubation experiments. J. Soil Sci. 36, 219-229. 

Somewhat different results were found in studies from the British Atomic Weapons Test Site at Maralinga, South Australia, where specific activities were noted to be greater in the soil size fractions >90 pm (Ellis and Wall, 1982). Presumably there are numerous factors that might influence the relationship of plutonium activity with soil particle size including the nature of the contaminating event, the degree of weathering since the contamination event, the chemical nature of the soil, and the particle size distribution of the soil. 

Christensen, B. T., Bertelsen, F., and Gissel-Nielsen, G., 1989, Selenite fixation by soil particle-size separates Journal of Soil Science, v. 40, p. 641-647. 

In Figure 2.2, the relationship between soil particle size and mineralogy is illustrated qualitatively, demonstrating the prevalence of secondary minerals in the clay fraction. The primary minerals, which originally formed under conditions of high temperature and pressure, are unstable in the soil environment. Consequently, primary minerals, when they are reduced to small particle size by physical weathering, tend to chemically decompose (weather) rapidly. Nevertheless, clay-sized quartz particles persist in soils because of the resistance of the quartz structure to chemical decomposition, as will be discussed later in this chapter, but even this mineral eventually dissolves as silica is leached from the soil. Thus we see that reaction rates... 

Tyler, S.W., and S.W. Wheatcraft. 1992. Fractal scaling of soil particle size distribution Analysis and limitations. Soil Sci. Soc. Am. J. 56 362—369. 

Adsorption Study. The adsorption of the test compounds by the sandy loam soil (particle size less than 35 mesh) was determined by measuring the difference in the concentration of an aqueous solution of each chemical, before and after equilibration with soil. Four to five concentrations per chemical were tested and three replicate measurements were performed at each concentration. Water-to-soil ratios of 2 1 to 10 1 were employed in all experiments. The time required to reach equilibrium was determined separately for each chemical at one concentration and a specific water-to-soil ratio. 

Saiz-Jimenez, C., Hermosin, B., Guggenberger, G. and Zech, W., Land use effects on the composition of organic matter in soil particle size separates. 3. Analytical pyrolysis, Eur. J. Soil ScL, 47, 61-69, 1996. 

Choudhry, F.A. (1988) Distribution of total inorganic and organic phosphate with respect to soil particle size. Thailand Journal of Agriculture Science 21,1 49-1 55. 

Under greenhouse conditions Peterburgsky and Smirnov (1966) observed that ammonium was used very poorly by plants. In these soils of the U.S.S.R. the chernozems fixed ammonium in considerably greater quantities than did podzolic soils. The ability to fix ammonium increased with decrease in soil particle size and also with profile depth. 

As stated in Section 5.2.1, soil is the primary source of radon. As such, radon is not released to soil but is the result of radioactive decay of radium-226 within the soil. The radon concentration in the soil is a function of the radium concentration, the soil moisture content, the soil particle size, and the rate of exchange of air with the atmosphere (Hopke 1987). Hopke (1987) states that normal soil-gas radon measurements are in the range of 270 to 675 pCi radon-222/L of air (10,000 to 25,000 Bq/m However, levels exceeding 10,000 pCi radon-222/L of air (370,000 Bq/m ) have been documented. 

Soil Particle-Size Analysis. The hydrometer method was used to perform a mechanical analysis of the soils (11). 

The percolation of a soil depends on the soil particle size and its chemical composition. Because of their small particle sizes, clays, and to a lesser degree sUts, tend to pack together in an impervious mass with litde or no percolation. Of course, sand, gravel, and rock pass water readily. Waterlogged soils that do not percolate support few crops because of their lack of air and oxygen. Rice, which requires water-logged soil, is an important exception. A... 

A rather crucial factor for the credibility of the results is the representativeness of sampling and the mass of test portion. The mass of test portion required depends on the maximum size of the soil particles. For example, the minimum mass of test portion normally used for a maximum soil particle size of 9.5 mm is 0.5 kg and that for a maximum soil particle size of 75 mm is 5 kg. 

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