On SO_4~(2-) Adsorption and Desorption Characteristics of Two Red Soils in Hunan Province

To study the characteristics of SO42- adsorption of different soil horizons from red soils in Hunan Province and the effect of solutions of different pH values on SO42- desorption of the these soils, the two red soils in Hunan Province are treated with different concentrations of (NH4)2SO4 solutions and solutions of different pH values through a batch experiment under laboratory conditions. The results show that the two tested red soils have a strong ability to absorb sulfate, and adsorption amount of SO42- rises with increasing soil depths when SO42- concentrations of input solutions are low. The desorption ratios of SO42- at the same soil horizons reduce with decreasing pH values when these soils are treated with solutions of different pH values.Meanwhile, the desorption ratios of SO42- at various soil horizons decrease with increasing soil depths when these soils are treated with solutions of the same pH values.When pH values of desorption solutions are lower than that of the tested soils , the effect of acidity of desorption solutions on SO42- desorption ratios of Changsha soils is more significant than those of Chenzhou soils;Because SO42- adsorption ablility of Changsha soil is stronger than that of Chenzhou soil and SO42- absorbed by Changsha soil is more difficult to be desorbed than SO42- absorbed by Chenzhou soil,Changsha soil has a greater ability to retain sulfate.