Cation exchange capacity of soil

Minnesota, Missouri, Oregon Cation exchange capacity of soil, in meq/100 g Low (<5) 5 kg Cd/surface ha 11... 

Perkins, A. T. Determination of cation-exchange capacity of soils by use... 

Schnitzer, M. (1965a). Contribution of organic matter to the cation exchange capacity of soil. Nature 207, 667-668. 

Biogeochemical cycle is intensive, but soil and ecosystems are sustainable to different types of pollutants, like acid rain, due to high buffering cation exchange capacity of soil. 

Cation Exchange Capacity of Soils Containing Calcium Carbonate... 

Relevant to expansive materials and based on total cation exchanged capacity of soil Values commonly range between 2.55 and 2.75 but a more accurate value is required for air voids determination. Only occasional checks are needed for most British soils, for which a value of 2.65 is assumed unless experience of similar soils shows otherwise Used in the calculation of forces exerted by soil... 

CALCINAI M. and SEQUI P. 1977. Contribution of organic matter to cation-exchange capacity of soils. In Soil Organic Matter Studies. IAEA Braunschweig, pp. 63-68. 

Dakshinamwite, C., and Chandool, D. E. (1966). Isoconductivity Values and Cation Exchange Capacity of Soils and Clays. Soil Sci. 102(2), 123-130. 

Methyl parathion is only slightly soluble in pH 7 water (55-60 ppm). This affects its mobility in water and its ability to be leached or solubilized into the water phase of a soil-water system. Factors most likely to affect the adsorption of methyl parathion in soil are organic matter content and cation exchange capacity. In soils of low organic matter (e.g., subsurface soils), calcium concentration, which affects the hardness of the water, may also be important (Reddy and Gambrell 1987). Several studies have shown... 

In addition to the crystalline clays described earlier, there are some materials that act like clays but do not have crystalline structure. Amorphous clays do not have a definite X-ray diffraction pattern and are differentiated from the crystalline clays on this basis. They are composed of mixtures of alumina, silica, and other oxides and generally have high sorptive and cation exchange capacities. Few soils contain large amounts of amorphous clays [2],... 

Also, the changes in pH will cause changes in the charges of variable-charge clays and organic matter, thus the cation exchange capacity of acid soils will tend to increase and that of alkaline soils decrease. 

Harada, Y. and Inoko, A. (1980) The measurement of the cation exchange capacity of composts for the estimation of the degree of maturity. Soil Science and Plant Nutrition 26, 127-134. 

Figure 11.9 Sorption isotherms for some charged organic compounds interacting with natural solids (a) quinolinium cation on a subsoil of /oc = 0.024 and cation exchange capacity of 84 mmol/kg (Zachara et al., 1986), ( >) anilinium cation on a surface soil with /oc = 0.013 and cation exchange capacity of 112 mmol/kg (Lee et al., 1997), and (c) sorption of 4-(2,4-dichloro-phe-noxy)-butyrate anion on a sediment with/oc = 0.015 and unknown anion exchange capacity (Jafvert, 1990).

Figure 11.15 Observed sorption of dodecylpyridinium on a soil (EPA-12) exhibiting an overall cation exchange capacity of 0.135 mol-kg"1. Two Langmuir isotherms (defined with particular values of C,s max and K/l, recall Eq. 9-5) are placed on the data to illustrate how different portions of the observed isotherm may reflect the influence of different materials in the complex soil sorbent or possibly different mechanisms (data from Brownawell et al., 1990).

Nitrification is limited in most soils by the supply rate of NH4+ (40, 41). Competition exists between nitrifiers and vegetation, which may both be limited by the availability of NH4 +. This microbial demand for NH4 +, coupled with the high cation-exchange capacity of most temperate forest soils, leads to surface-water NH4+ concentrations that are usually undetectable. Nitrification rates may also be limited by inadequate microbial populations, lack of water, allelopathic effects (toxic effects produced by inhibitors manufactured by vegetation), or by low soil pH. 

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. 

Barium is also adsorbed onto soil and subsoil through electrostatic interactions (Bodek et al. 1988 Singer 1974). The cation exchange capacity of the sorbent largely controls the retention of barium in soils (Bodek et al. 1988). Barium is strongly adsorbed by clay minerals (Kabata-Pendias and Pendias 1984 Lagas et al. 1984). 

The insolubility of Al(OH)3 and the diffusion of C02 to the atmosphere drive this reaction to completion. Also, adsorption of cations onto the colloid complex raises the percentage base saturation (extent to which the colloidal complex is saturated with exchangeable cations other than hydrogen and aluminum, expressed as a percentage of the total cation exchange capacity) of the colloidal complex, increasing the pH of the soil solution accordingly. 

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