Study of fluorine retention capacity of red earths
1988
Liu Zhonghan (Yunnan Provincial Inst. of Environmental Science, (China))
With the aim of determining the fluorine retention capacity of red earths and the fluoride migration in the soils after the soluble fluoride entered into soils, the experiments of isothermic adsorption and desorption and those of soil core leaching on red earths derived from limestone, basalt and sandstone were conducted. The results of study showed that the net adsorption capacity of F by soil was affected by parent material texture and mineral composition of soils, the net adsorption capacity of F by the red earths derived from limestone, basalt and sandstone were 740, 464 and 244 ug F-/g soil respectively. It is considered that net capacity of F may be used as a better indicator for fluorine retention capacity of soil than the adsorption capacity or the maximum adsorption capacity. The results also showed the contents of water-soluble F, exchangeable F, citric acid extractable and 0.5 NHCL extractable F were very different in the soil with similar total F content and same parent material due to the difference in other soil properties. This indicates the desorption of F in soil is of most importance for F retention capacity of soil.
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