Water-saturated soil

Electrolytic method This procedure is also known as the Williams Corfleld test d. It is based on loss of metal from iron electrodes buried in a water-saturated soil through which current from a 6-V battery is passed. It does not reflect field conditions and depends upon soil conductance under saturated conditions. 

Roy WR, Griffin RA. 1985. Mobility of organic solvents in water-saturated soil materials. Environ Geol Water Sci 7 241-247. 

Possible environmental applications of NIR probes include the measurement of trace amounts of metal pollutants in surface and ground waters and water saturated soils and sediments and the detection of lead, chromium, and other heavy metal ions for efforts in pollution control. Also OFCD could assist in the determination of caustic soda and chlorine contents in wastewaters. 

Another example of biotically induced Fe oxide formation is found in the rhizosphere of the higher plants growing in strictly anaerobic, i.e. water saturated, soils at low Eh. 

Davidson, J.M., McDougal, J.R. (1973) Experimental and predicted movement of three herbicides in a water-saturated soil. J. Environ. Qual. 2, 428-433. 

Natural convective flows in porous media occur in a number of important practical situations, e.g., in air-saturated fibrous insulation material surrounding a heated body and about pipes buried in water-saturated soils. To illustrate how such flows can be analyzed, e.g., see [20] to [22], attention will be given in this section to flow over the outer surface of a body in a porous medium, the flow being caused purely by the buoyancy forces resulting from the temperature differences in the flow. The simplest such situation is two-dimensional flow over an isothermal vertical flat surface imbedded in a porous medium, this situation being shown schematically in Fig. 10.25. 

A heat pump system utilizes a heat exchanger buried in water-saturated soil as a heat source. The heat exchanger basically consists of a series of vertical plates with height of 30 cm and a width of 10 cm. These plates are effective Is at a uniform temperature of 5°C. The soil can be assumed to have a permeability of 10 0 nr and apparent thermal conductivity of 0.1 W/m-K. The temperature of the saturated soil far from the heat exchanger is 30°C. Assuming natural convective flow and that there is no interference between the flows over the individual plates, find the mean heat transfer rate to a plate. 

Vacuum extraction involves aeration followed by vacuum. It represents one of the most commonly used in situ treatment technologies. The technigue is effective when employed under buildings it is relatively cost effective but lengthy, and is not effective in water-saturated soils. 

Roy, W.R., Griffin, R.A. (1985) Mobility of organic solvents in water-saturated soil materials. Environ. Geol. Water Sci. 7, 241-247. Russell, C.J., Dixon, S.L., Jurs, PC. (1992) Computer-assisted study of the relationship between molecular structure and Henry s law constant. Anal. Chem. 64, 1350-1355. 

The experimental investigations show that H2S does not migrate in the gas phase through soil. However, it migrates through water-saturated soil, probably in solution as sulphide anions and compounds. These are subsequently adsorbed onto soil particles, from which they can be released as H2S. This can be determined in concentrations as low as 0.01 mg using lead acetate paper. 

The removal of dissolved or particulate organic contaminants is most effective where they can be aerobically broken down. Aerobic decay is most rapid in well-aerated, unsaturated soils and is most complete in thick, unsaturated soils. Organic decay in water-saturated soils tends to be anaerobic, which is much slower and produces more noxious products than aerobic decay (see Chap. 5). Because the O and A horizons of a soil are usually relatively acid (cf. Figs. 7.2 and 7.3), the alkalinity of soils chiefly resides in the clays and carbonates within B and C horizons. Because of their carbonate content, mollisols and aridisols can neutralize acid wastes more rapidly and completely than can oxisols and spodosols, for example. 

Other important reductants dissolved in water-saturated soils and sediments include ammonia, hydrogen sulfide, Mn, and Fe. Table 11.4 shows that organic carbon (depending on its oxidation state) is generally a stronger reductant on a mole basis than any of these. Organic carbon is also usually more abundant than other potential reductants, particularly in modern aquatic sediments. 

Because reductants are present in most water-saturated soils or sediments and oxygen is relatively unavailable, the Eh declines as the water moves into the subsurface. The decline may be from oxic to anoxic sulfidic or nonsulfidic levels (Table 11.5). The rate and extent of Eh decline with distance from the surface depends on the availability and reactivity of sediment organic matter and other reductants. In the sediments of flooded rice paddies, wetlands, estuaries, and shallow lakes, which may be especially rich in fresh organic matter, the redox front or intetface (also termed a redox barrier or boundary by some), which is the zone of abruptly changing Eh values, may be only a few millimeters or centimeters thick. 

Hornsby, A.G., and J.M. Davidson. 1973. Solution and adsorbed fluometuron concentration distribution in a water-saturated soil Experimental and predicted evaluation. Soil Sd. Soc. Am. Proc. 37 823-828. 

Chapter 9 gave an equation that predicted the rate of advance, vm, of metal pollutants, M, through a water-saturated soil column if the velocity of water flow, v, through the column was known. This same equation could in principle predict the movement of low levels of an organic pollutant, assuming that sorption is reversible ... 

Conversely, if, for any reason, steel within concrete is no more passive, the presence of ground systems may be dangerous, since these connections offer a large and practically unpolarised cathodic area. In addition, since the anodic and cathodic areas are far apart, they may be operating under very different environmental conditions. For example, the anodic area may be in contact with water-saturated concrete (therefore in an anaerobic but highly conductive environment) because it is surrounded by water-saturated soil at the same time the cathodic area may be found in a soil that is completely aerated. 

The shrinkage curve during drying was measured with a previously published procedure [19]. The water saturated soil samples were placed on a balance to measure loss of water during drying. At the same time, the linear shrinkage of the height and diameter of each sample is measured by three laser spots. The data were recorded and converted to specific volume and water content [19]. 

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