Some Aspects of the Salinity of Mancos Shale and Mancos Derived Soils
Initial studies to determine the thermodynamic solubility product (Ksp) of gypsum and CaCO3 were conducted. The influence of different electrolyte salts at different concentrations upon the solubility of gypsum and CaCO3 was then tested. Analytical data was utilized in conjunction with a computer to...
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| Format: | Others |
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DigitalCommons@USU
1976
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| Online Access: | https://digitalcommons.usu.edu/etd/3212 https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=4213&context=etd |
| Summary: | Initial studies to determine the thermodynamic solubility product (Ksp) of gypsum and CaCO3 were conducted. The influence of different electrolyte salts at different concentrations upon the solubility of gypsum and CaCO3 was then tested. Analytical data was utilized in conjunction with a computer to calculate the activity of CaCO3 and gypsum, the ion pair concentration and the solubility product. Indifferent salts increased the solubility of gypsum and CaCO3, and salts with a common ion decreased the solubility of gypsum and CaCO3.
Lithium was found to be the dominant monovalent cation present in these marine derived soils. In most cases the lithium concentration was greater than the sodium plus potassium (Na++K+) concentrations. All soils were found to be high in calcium and sulfate and the 1:1 soil water suspensions were saturated with respect to the constituent mineral gypsum.
Salt release from Mancos shale is controlled by the parabolic diffusion law. Two diffusion controlled reactions occur: (a) a fast surface reaction and (b) a slow mineral weathering reaction. The fast reaction, accounting for 80-90 percent of the total salt production is due to the dissolution of salt from the surface of the mineral particles and to the dissolution of the fine (<.10 mm) mineral fraction. This reaction occurred in less than 2 minutes. The slow reaction accounting for 10-20 percent of the salt production is due to the dissolution of the larger more resistant mineral fraction, and proceeds for several days.
Chemical equilibrium was reached in less than 72 hours for the small natural occurring size fraction (<.10 mm), while 7 to 9 days was required for equilibrium in the larger (>.25 to >1.0 mm) size fractions, respectively.
Soil columns were leached with deionized water to allow the calculation of potential to produce 3.15 tons of salt per acre inch, and the salt accounted for 1.89 percent of the soil's total mass. |
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