Soil, liquid phase

The most important factor influencing the uptake of strontium by plants is the Ca status of the soil, other factors include the pH and organic matter content. Lem-brechts et al. (1990) have investigated the relation between soil solution composition and 85Sr uptake by young lettuce plants. A close relationship was shown between the Sr concentrations in the plants and the Sr/Ca ratio in solution either in nutrient medium, or in soil solution. It was suggested that plants primarily withdraw their nutrients from the soil liquid phase. 

The soil liquid phase has a composition and reactivity defined by the properties of the incoming water and fluxes of matter and energy originating from the local (neighbouring) soil solid phase, biological system and atmosphere (Fig. 10.1). 

Figure 10.1 Biogeochemical cycling of soil contaminants the soil liquid phase is acting as a regulator of contaminant fate (modified from Hesterberg, 1998, based on Lindsay, 1979 Mattigod et al., 1981).

Reactions across the interface between colloid crystals and the soil liquid phase may also suppress the availability of nutrient elements to plants. The effectiveness of these interfacial reactions in supporting optimum plant growth ultimately depends on the arrangements of ions in the surfaces and subsurfaces of the mineral crystals. For this reason much of this volume is devoted to the arrangement of ions in crystalline mineral particles commonly occuring in soils and the properties that these particles contribute to soil systems. 

The liquid phase of the soil system is the soil water, or the soil solution as it is more appro-... 

In addition to these relatively simple liquid phase aqueous systems, it is necessary to identify situations in which any of these aqueous phase reservoirs come into physical and chemical contact with solid surfaces (e.g., rocks, biomass, sediments, soils, magma etc.). In general, the presence of two or more phases (liquid plus one or more solid phase) provides important constraints on the chemical reactions that may occur within the system as a whole. 

In an SVE system, the primary mechanism for contaminant removal from the soil to the vadose zone is the volatilization of contaminants present in the pure or adsorbed phase onto soil into the vapor phase, as the vapor phase is continually extracted. The property that shows the extent to which this transfer can take place during SVE is vapor pressure, which provides an indication of the extent to which each contaminant will partition between the liquid phase and the vapor state at equilibrium conditions. Generally, a contaminant with a greater vapor pressure more readily volatilizes than one with a lesser vapor pressure. 

Fig. 5. Relationship between the log Koc for phenanthrene sorption and the aliphaticity of humic acids, sequentially extracted from a soil. F-l, F-4, F-7, and F-9 are the first, fourth, seventh, and nineth extracted humic acids, respectively. 0.005, 0.05, and 0.5 pg mL are selected liquid-phase equilbrium concentrations of phenanthrene (Kang and Xing 2005).

Boesten JJTI (1993) Bioavailability of organic chemicals in soil related to then-concentration in the liquid phase a review. Sci Tot Environ Supplement 397-407... 

Thus, in according to the concept of equilibrium distribution, the relation of an organic pollutant concentration in the soil solid and liquid phase is constant at any moment (Vasilyeva and Shatalov, 2004). The example of such an approach application for assessing exposure pathways of POPs to living biota is shown in Box 1. 

In 1938 Soil filed a patent1 covering the treatment of rubbers with diluted F2 to improve their resistance with regard to F2 reactivity. Interestingly, he also suggested the possibility of liquid-phase fluorination, a principle that was later further explored and patented for surface fluorination.2... 

The chemistry of soil is contained in the chemistry of these three phases. For the solid phase, the chemistry will depend on the amount and type of surface available for reaction. In the liquid phase, solubility will be the most important characteristic for determining the chemistry occurring. In the gaseous phase, gas solubility and the likelihood that the component can be in the gaseous form (i.e., vapor pressure) will control reactivity. 

All components in the soil solution are to a greater or lesser extent distributed unevenly between the solid and liquid phases. Anions are generally only... 

Two types of distribution coefficients are commonly measured and used in describing the distribution between solid and liquid phases. The first and simplest is the distribution between total solid and liquid phases. This can be represented by Kd, as given in the equation in Figure 5.11. Here, kg is kilogram and L is liter of soil solution. 

Walters and Guiseppe-Elle [108] studied the sorption of 2,3,7,8-tetrachlorodibenzo-p-dioxin to soils from aqueous methanol mixtures and evaluated the applicability of the cosolvent theory to such sorption. Sorption kinetics were influenced by the fraction of methanol in the liquid phase and the soil type. Linear equilibrium sorption isotherms were... 

Liquid phase migration and retention — NAPL held suspended by the water table or capillary fringe or perched above low permeability zones (water wet soil) in the unsaturated zone. 

Injection of steam or heated air into the subsurface provides large amounts of thermal energy, which speeds the mobilization of adsorbed organic contaminants and results in their removal as either a vapor or liquid phase. Elevated temperature increases the vapor pressure of the chemicals involved and promotes transfer of constituents across the air-water interface, which results in the increased removal of contaminants in high-humidity or nearly saturated soil systems. Additionally, the presence of high-temperature water sometimes results in oxidation or hydration of organic contaminants. 

Under most circumstances microorganisms are attached to solid soil particles and await the arrival of water, nutrients, and electron acceptors. When the biomass is above the water table, the dependence is upon migration of nutrients and diffusion of oxygen downward (or upward via capillary action). Bacterial colonies that develop below the saturated zone are dependent upon liquid phases for the delivery of necessary growth media. 

Four different methods (vapour-phase acetylation using acetic anhydride, acetylation using ketene gas, liquid phase acetylation using acetic anhydride/xylene, or neat acetic anhydride) were used to acetylate pine wood chips to a variety of WPGs for the production of MUF-bonded particleboards (Nilsson etal., 1988). Composite boards were exposed to unsterile soil in fungal cellar tests. Boards made from ketene acetylated chips were not found to be resistant to decay at the maximum WPG level achieved (17 %) with a liquid acetic anhydride modification, no decay was recorded at a WPG level of c. 18 % after 12 months exposure, whereas with a vapour-phase treatment at the same WPG, evidence for decay was found. 

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